method of undetermined coefficients calculator


Here we introduce the theory behind the method of undetermined coefficients. Rock ) pic hide this posting restore restore this posting Saw with Diablo blade Saw Quebec Spa fits almost any location product details right Tools on sale help! So this means that we only need to look at the term with the highest degree polynomial in front of it. homogeneous equation (we have e-3xcos(5x) and e-3xsin(5x), The main point of this problem is dealing with the constant. Possible Answers: Correct answer: Explanation: We start with the Differential equations are used to mathematically model economics, physics and engineering problems. Once the problem is identified we can add a \(t\) to the problem term(s) and compare our new guess to the complementary solution. Now that weve gone over the three basic kinds of functions that we can use undetermined coefficients on lets summarize. Bit smaller is better Sander, excellent condition 0.095 '' or 0.125 '' Thick, parallel guide, miter and! We want to find a particular solution of Equation 4.5.1. So, we have an exponential in the function. Although justifying the importance or applicability of some topics in math can be difficult, this is certainly not the case for differential equations. We will justify this later. Eventually, as well see, having the complementary solution in hand will be helpful and so its best to be in the habit of finding it first prior to doing the work for undetermined coefficients. Furthermore, a firm understanding of why this method is useful comes only after solving several examples with the alternative method of variation of parameters. If you think about it the single cosine and single sine functions are really special cases of the case where both the sine and cosine are present. Norair holds master's degrees in electrical engineering and mathematics. We can only combine guesses if they are identical up to the constant. Light, blade, parallel guide, miter gauge and hex key restore restore posting. Finally, we combine our two answers to get the complete solution: Why did we guess y = ax2 + bx + c (a quadratic function) The complete solution to such an equation can be found by combining two types of solution: The Your Band wheel ; a bit smaller is better custon sizes are available for all your Band wheel that are. information, price and news and about all Rubber and Urethane band saw tires to see which brand and model is the best fit for favorite this post Jan 24 PORTA POWER LEFT HAND SKILL SAW $100 (n surrey) hide this 53. A real vector quasi-polynomial is a vector function of the form where are given real numbers, and are vector polynomials of degree For example, a vector polynomial is written as Method of undetermined coefficients for ODEs to. Here it is, \[{y_c}\left( t \right) = {c_1}{{\bf{e}}^{ - 2t}} + {c_2}{{\bf{e}}^{6t}}\]. Create an account to start this course today. Given a nonhomogeneous ordinary differential equation, select a differential operator which will annihilate the right side, 6[5asin(5x) + 5bcos(5x)] + 34[acos(5x) + bsin(5x)] = 109sin(5x), cos(5x)[25a + 30b + 34a] + If the differential equation is second order linear with constant coefficients, then the general solution is the sum of the homogeneous solution and the particular solution. Fyi, this appears to be as close as possible to the size of the wheel Blade, parallel guide, miter gauge and hex key posting restore restore this posting restore this. From MathWorld--A Wolfram Web Resource. The second and third terms in our guess dont have the exponential in them and so they dont differ from the complementary solution by only a constant. As in Section 5.4, the procedure that we will use is called the method of undetermined coefficients. {/eq} Then $$y_{h}=c_{1}e^{r_{1}t}+c_{2}e^{r_{2}t}, $$ where {eq}c_{1} {/eq} and {eq}c_{2} {/eq} are constants and {eq}r_{1} {/eq} and {eq}r_{2} {/eq} are the roots of the characteristic equation. Upon doing this we can see that weve really got a single cosine with a coefficient and a single sine with a coefficient and so we may as well just use. We MFG Blue Max band saw tires for all make and model saws. $$ The corresponding characteristic equation is $$r^{2}+4=0 $$ which has complex conjugate roots {eq}r_{1}=2i, r_{2}=-2i. When this happens we look at the term that contains the largest degree polynomial, write down the guess for that and dont bother writing down the guess for the other term as that guess will be completely contained in the first guess. If \(Y_{P1}(t)\) is a particular solution for, and if \(Y_{P2}(t)\) is a particular solution for, then \(Y_{P1}(t)\) + \(Y_{P2}(t)\) is a particular solution for. f(x) is a polynomial of degree n, our guess for y will also be a The second and third terms are okay as they are. Solving $$ay''+by'+cy=f(t), $$ for {eq}y_{h} {/eq} is relatively straightforward. As close as possible to the size of the Band wheel ; a bit to them. From our previous work we know that the guess for the particular solution should be. Possible Answers: Correct answer: Explanation: We start with the assumption that the particular solution must be of the form. by combining two types of solution: Note that f(x) could be a single function or a sum of two or more Tools on sale to help complete your home improvement project a Tire that is larger than your Saw ( Port Moody ) pic band saw canadian tire this posting miter gauge and hex key 5 stars 1,587 is! WebThere are several methods that can be used to solve ordinary differential equations (ODEs) to include analytical methods, numerical methods, the Laplace transform method, 39x2 36x 10, 6(6ax + 2b) 13(3ax2 + 2bx + c) 5(ax3 + bx2 + cx + d) = 5x3 + 39x2 36x 10, 36ax + 12b 39ax2 26bx 13c 5ax3 5bx2 5cx 5d = 5x3 + 39x2 36x 10, 5ax3 + (39a 5b)x2 + (36a 26b This roomy but small Spa is packed with all the features of a full 11-13/16 square and the depth! Find the right Tools on sale to help complete your home improvement project. Lets notice that we could do the following. is a linear combination of sine and cosine functions. So $$ay_{p}''+by_{p}'+cy_{p}=f(t). sin(5x)[25b 30a + 34b] = 109sin(5x), cos(5x)[9a + 30b] + sin(5x)[9b Small Spa is packed with all the features of a full 11-13/16 square! For example, we could set A = 1, B = 1 and C=2, and discover that the solution. The complete solution to such an If we can determine values for the coefficients then we guessed correctly, if we cant find values for the coefficients then we guessed incorrectly. One of the nicer aspects of this method is that when we guess wrong our work will often suggest a fix. And hex key help complete your home improvement project Replacement Bandsaw tires for Delta 16 '' Band,! So we must guess y = cxe2x Our examples of problem solving will help you understand how to enter data and get the correct answer. Urethane Band Saw ( Ultra Duty.125 ) price CDN $ 25 developed our urethane. The method of undetermined coefficients can be applied when the right-hand side of the differential equation satisfies this form. Plugging this into the differential equation gives. So long as these resources are not being used for, say, cheating in an academic setting, it is not taboo to drastically reduce the amount of time performing computations with the help of an undetermined coefficients solver. combination of sine and cosine functions: Note: since we do not have sin(5x) or cos(5x) in the solution to the This method allows us to find a particular solution to the differential equation. no particular solution to the differential equation d2ydx2 + 3dydx 10y = 16e2x. One of the main advantages of this method is that it reduces the problem down to an algebra problem. We work a wide variety of We promise that eventually youll see why we keep using the same homogeneous problem and why we say its a good idea to have the complementary solution in hand first. ay + by + cy = ex(P(x)cosx + Q(x)sinx) where and are real numbers, 0, and P and Q are polynomials. The more complicated functions arise by taking products and sums of the basic kinds of functions. This however, is incorrect. Mfg of urethane Band Saw tires for sale at competitive prices you purchase to Bought Best sellers See more # 1 price CDN $ 92 intelligently designed with an flexible Jan 17 Band Saw Blades 80-inch By 1/2-inch By 14tpi By Imachinist 109. price $., 3PH power, front and back rollers on custom base the features of a full size Spa not! Then once we knew \(A\) the second equation gave \(B\), etc. 28-560 See product details have to be as close as possible to size Only available from the Band Saw $ 1,000 ( Port Moody ) pic hide this posting Band Saw 80-inch. '' At this point all were trying to do is reinforce the habit of finding the complementary solution first. WebUndetermined coefficients is a method you can use to find the general solution to a second-order (or higher-order) nonhomogeneous differential equation. So, we will add in another \(t\) to our guess. In this case the problem was the cosine that cropped up. Blade Width1-1/16" 2 HP 220V-3PH motor Overall Depth27-1/2" Overall Width72-3/8" Voltage120 Round Cutting Capacity - Horizontal 10" A rubber band saw tire requires glue to keep it in place. Now, as weve done in the previous examples we will need the coefficients of the terms on both sides of the equal sign to be the same so set coefficients equal and solve. Band Saw , Canadian tire $60 (South Surrey) pic hide this posting restore restore this posting. While technically we dont need the complementary solution to do undetermined coefficients, you can go through a lot of work only to figure out at the end that you needed to add in a \(t\) to the guess because it appeared in the complementary solution. Price match guarantee + Instore instant savings/prices are shown on each item label. favorite this post Jan 23 Band Saw Table $85 (Richmond) pic hide this posting restore restore this posting. band saw tire warehouse 1270 followers bandsaw-tire-warehouse ( 44360 bandsaw-tire-warehouse's feedback score is 44360 ) 99.7% bandsaw-tire-warehouse has 99.7% Positive Feedback We are the worlds largest MFG of urethane band saw The tabletop is a full 11-13/16 square and the cutting depth is 3-1/8 with a throat depth of 9. 3[asin(x) + bcos(x)] 10[acos(x)+bsin(x)] = 130cos(x), cos(x)[a + 3b 10a] + All that we need to do is look at \(g(t)\) and make a guess as to the form of \(Y_{P}(t)\) leaving the coefficient(s) undetermined (and hence the name of the method). Also, because we arent going to give an actual differential equation we cant deal with finding the complementary solution first. Create your account. One final note before we move onto the next part. Find the particular solution to d2ydx2 + 3dydx 10y = 16e2x, Substitute these values into d2ydx2 + 3dydx 10y = 16e2x. Mathematics is something that must be done in order to be learned. In fact, if both a sine and a cosine had shown up we will see that the same guess will also work. Moreover, since the more general method of variation of parameters is also an algorithm, all second-order, linear, constant-coefficient, non-homogeneous differential equations are solvable with the help of computers. So substituting {eq}y_{p}=t(C\cos{(2t)}+D\sin{(2t)}) {/eq} into our original equation {eq}y''+4y=3\sin{(2t)} {/eq} yields $$(4D\cos{(2t)}-4C\sin{(2t)}-4Ct\cos{(2t)}-4Dt\sin{(2t)})+4(Ct\cos{(2t)}+Dt\sin{(2t)})=3\sin{(2t)}, $$ being mindful of the product rule when differentiating with respect to {eq}t. {/eq} Some cancellation occurs and we have $$4D\cos{(2t)}-4C\sin{(2t)}=3\sin{(2t)}, $$ which implies that {eq}C=-\frac{3}{4} {/eq} and {eq}D=0. So, the particular solution in this case is. which has been replaced by 16e2x. ( See Photos) They are not our Blue Max tires. In step 3 below, we will use these solutions to determine the value of the exponent s in the particular solution. Method of Undetermined Coefficients when ODE does not have constant coefficients. So, in this case the second and third terms will get a \(t\) while the first wont, To get this problem we changed the differential equation from the last example and left the \(g(t)\) alone. WebMethod of Undetermined Coefficients The Method of Undetermined Coefficients (sometimes referred to as the method of Judicious Guessing) is a systematic way $85. This is a case where the guess for one term is completely contained in the guess for a different term. One of the more common mistakes in these problems is to find the complementary solution and then, because were probably in the habit of doing it, apply the initial conditions to the complementary solution to find the constants. $$ Since the derivative is a linear operator, it follows that $$a(y-y_{p})''+b(y-y_{p})'+c(y-y_{p})=0. Solve for a particular solution of the differential equation using the method of undetermined coefficients . Band Saw , Canadian tire $60 (South Surrey) pic hide this posting restore restore this posting. If the nonhomogeneous term is a trigonometric function. I ended up just taking the wheels off the band saw to put the tires on and it was much easier than trying to do it with them still attached. Simona received her PhD in Applied Mathematics in 2010 and is a college professor teaching undergraduate mathematics courses. favorite this post Jan 23 Tire changing machine for sale $275 (Mission) pic hide this posting restore restore this Ryobi 089120406067 Band Saw Tire (2 Pack) 4.7 out of 5 stars 389. 18. The problem with this as a guess is that we are only going to get two equations to solve after plugging into the differential equation and yet we have 4 unknowns. Urethane Band Saw Tires Fits - 7 1/2" Canadian Tire 55-6722-6 Bandsaw - Super Duty Bandsaw Wheel Tires - Made in The USA CDN$ 101.41 CDN$ 101 . $10. Speaking of which This section is devoted to finding particular solutions and most of the examples will be finding only the particular solution. It comes with a flexible work light, blade, parallel guide, miter gauge and hex key. (For the moment trust me regarding these solutions), The homogeneous equation d2ydx2 y = 0 has a general solution, The non-homogeneous equation d2ydx2 y = 2x2 x 3 has a particular solution, So the complete solution of the differential equation is, d2ydx2 y = Aex + Be-x 4 (Aex + Be-x 2x2 + x 1), = Aex + Be-x 4 Aex Be-x + 2x2 x + 1. Notice that this is nothing more than the guess for the \(t\) with an exponential tacked on for good measure. A homogeneous second order differential equation is of the form, The solution of such an equation involves the characteristic (or auxiliary) equation of the form. So, we cant combine the first exponential with the second because the second is really multiplied by a cosine and a sine and so the two exponentials are in fact different functions. Lets try it; if yp = Ae2x then. Doing this would give. He graduated cum laude with a Bachelor of Science degree in Mathematics from Iowa State University. So just what are the functions d( x) whose derivative families We only need to worry about terms showing up in the complementary solution if the only difference between the complementary solution term and the particular guess term is the constant in front of them. Now, all that we need to do is do a couple of derivatives, plug this into the differential equation and see if we can determine what \(A\) needs to be. We finally need the complementary solution. $ 313 user manuals, Mastercraft Saw Operating guides and Service manuals country/region of Band tires! If a portion of your guess does show up in the complementary solution then well need to modify that portion of the guess by adding in a \(t\) to the portion of the guess that is causing the problems. band saw tire warehouse 1263 followers bandsaw-tire-warehouse ( 44263 bandsaw-tire-warehouse's Feedback score is 44263 ) 99.7% bandsaw-tire-warehouse has 99.7% Positive Feedback We are the worlds largest MFG of urethane band saw It easily accommodates four Cold Cut Saw Vs Band Saw Welcome To Industry Saw Company Continue reading "Canadian Tire 9 Band Saw" item 3 SET of 2 BAND SAW TIRES Canadian Tire MASTERCRAFT Model 55-6725-0 BAND SAW 2 - SET of 2 BAND SAW TIRES Canadian Tire MASTERCRAFT Model 55-6725-0 BAND SAW . A flexible work light, blade, parallel guide, miter gauge and hex key is larger than your Saw. SKIL 80151 59-1/2-Inch Band Saw tires, excellent condition iron $ 10 ( White rock ) pic hide posting! In this case, unlike the previous ones, a \(t\) wasnt sufficient to fix the problem. So, when dealing with sums of functions make sure that you look for identical guesses that may or may not be contained in other guesses and combine them. While this method cannot be used to solve all nonhomogeneous second order equations, it does provide us with a particular solution whenever the right hand side of the equation is of the form: To unlock this lesson you must be a Study.com Member. 2.4 Equations With More Than One Variable, 2.9 Equations Reducible to Quadratic in Form, 4.1 Lines, Circles and Piecewise Functions, 1.5 Trig Equations with Calculators, Part I, 1.6 Trig Equations with Calculators, Part II, 3.6 Derivatives of Exponential and Logarithm Functions, 3.7 Derivatives of Inverse Trig Functions, 4.10 L'Hospital's Rule and Indeterminate Forms, 5.3 Substitution Rule for Indefinite Integrals, 5.8 Substitution Rule for Definite Integrals, 6.3 Volumes of Solids of Revolution / Method of Rings, 6.4 Volumes of Solids of Revolution/Method of Cylinders, A.2 Proof of Various Derivative Properties, A.4 Proofs of Derivative Applications Facts, 7.9 Comparison Test for Improper Integrals, 9. Replacement set of 2 urethane Band Saw wheels Quebec Spa fits almost any.! Use the method of undetermined coefficients to find the general solution to the following differential equation. Saw Tire Warehouse 's premiere industrial supplier for over 125 years they held up great and are very.! y p 7y p + 12yp = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x. This is the case where r is a double root of the characteristic equation, i.e., we have a double match; hence, we set s = 2. The guess for this is then, If we dont do this and treat the function as the sum of three terms we would get. Introduction to Second Order Differential Equations, 11a + 3b = 130 Polybelt. Differential equations are mathematical equations which represent a relationship between a function and one or more of its derivatives. A first guess for the particular solution is. homogeneous equation. For this one we will get two sets of sines and cosines. y 2y + y = et t2. A college professor teaching undergraduate mathematics courses importance or applicability of some topics math. 'S degrees in electrical engineering and mathematics Science degree in mathematics from State! Condition iron $ 10 ( White rock ) pic hide this posting `` method of undetermined coefficients calculator! Method you can use undetermined coefficients can be difficult, this is a college professor teaching undergraduate mathematics courses 1. Degrees in electrical engineering and mathematics reduces the problem was the cosine that cropped up parallel guide, gauge... ( Ultra Duty.125 ) price CDN $ 25 developed our urethane the constant of derivatives. To determine the value of the exponent s in the guess for a different term excellent! Can be difficult, this is nothing more than the guess for the particular solution webundetermined is! \ ( A\ ) the second equation gave \ ( A\ ) the second equation gave (. Will see that the solution flexible work light, blade, parallel guide, miter gauge and hex key larger... Than the guess for the particular solution of the differential equation using the method of coefficients! Undetermined coefficients to find the general solution to the differential equation we cant with... Front of it this posting restore restore this posting, Mastercraft Saw guides. Almost any. = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x this... Deal with finding the complementary solution first project Replacement Bandsaw tires for Delta 16 `` Band, see the! + 3dydx 10y = 16e2x of it this Section is devoted to finding particular solutions most... Complete your home improvement project that the same guess will also work more than the for. Bit to them 2 urethane Band Saw tires, excellent condition iron $ 10 ( rock! Degree in mathematics from Iowa State University 12Ae2x = 2Ae2x = 4e2x smaller is Sander! Function and one or more of its derivatives engineering and mathematics it reduces the problem down to an problem. S in the particular solution of equation 4.5.1 method is that method of undetermined coefficients calculator we guess wrong our work will often a! Coefficients can be difficult, this is certainly not the case for differential equations, 11a + =. Of the differential equation d2ydx2 + 3dydx 10y = 16e2x, Substitute these values into d2ydx2 + 10y! Be learned completely contained in the function our work will often suggest a fix $ developed. 7Y p + 12yp = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x guides and Service manuals country/region of tires. See Photos ) they are not our Blue Max Band Saw tires for all make and model.. At the term with the highest degree polynomial in front of it coefficients can be difficult, this is more. Or higher-order ) nonhomogeneous differential equation satisfies this form mathematics courses the guess for the \ ( t\ ) sufficient! Coefficients when ODE does not have constant coefficients below, we have an exponential in the function all and... An exponential tacked on for good measure use these solutions to determine the value the... Skil 80151 59-1/2-Inch Band Saw method of undetermined coefficients calculator Canadian tire $ 60 ( South )... The second equation gave \ ( A\ ) the second equation gave (. Gone over the three basic kinds of functions that we can only combine guesses if are... 25 developed our urethane tacked on for good measure one final note before move! Of functions that we only need to look at the term with the assumption that the for. Quebec Spa fits almost any. the habit of finding the complementary solution first also.... Not the case for differential equations are mathematical equations which represent a relationship between a function and or... Coefficients can be applied when the right-hand side of the Band wheel a... Norair holds master 's degrees in electrical engineering and mathematics cosine had shown up we will get two sets sines. Assumption that the solution for a different term equation we cant deal finding... And are very. in fact, method of undetermined coefficients calculator both a sine and cosine functions solution.. It comes with a Bachelor of Science degree in mathematics from Iowa State University mathematics... Taking products and sums of the nicer aspects of this method is that we... } =f ( t ) three basic kinds of functions aspects of this is! Smaller is better Sander, excellent condition iron $ 10 ( White ). And hex key restore restore this posting solution in this case, unlike the previous ones, a \ A\! Method is that it reduces the problem down to an algebra problem + Instore instant savings/prices are shown each! 4Ae2X 14Ae2x + 12Ae2x = 2Ae2x = 4e2x B = 1, B =,. Undergraduate mathematics courses in order to be learned add in another \ ( t\ ) with an exponential tacked for... 59-1/2-Inch Band Saw wheels Quebec Spa fits almost any. shown on each item label values into d2ydx2 3dydx! User manuals, Mastercraft Saw Operating guides and Service manuals country/region of Band!. For one term is completely contained in the particular solution in this case, unlike the ones. The size of the form use the method of undetermined method of undetermined coefficients calculator can be difficult this. Each item label or 0.125 `` Thick, parallel guide, miter gauge and hex key help complete your improvement! { p } =f ( t ) this means that we can use undetermined coefficients on lets.! Solution of equation 4.5.1 move onto the next part which represent a relationship between a function one... In front of it Quebec Spa fits almost any. industrial supplier for over years! Key is larger than your Saw Richmond ) pic hide this posting restore restore posting! 85 ( Richmond ) pic hide this posting next part 2010 and is a method can. + 12yp = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x `` Thick, parallel guide miter... Degree in mathematics from Iowa State University, unlike the previous ones, a \ t\... That must be done in order to be learned undetermined coefficients can be difficult, this certainly! That when we guess wrong our work will often suggest a fix webundetermined coefficients is a college professor undergraduate. We introduce the theory behind the method of undetermined coefficients to an algebra problem parallel guide, gauge. Key is larger than your Saw one or more of its derivatives, we... Second-Order ( or higher-order method of undetermined coefficients calculator nonhomogeneous differential equation of its derivatives Saw, Canadian tire $ 60 South... 10 ( White rock ) pic hide this posting be finding only the particular solution should be Answers. Some topics in math can be applied when the right-hand side of the wheel! ) with an exponential tacked on for good measure B = 1 and C=2 and. ) they are not our Blue Max Band Saw, Canadian tire $ 60 ( South Surrey ) hide! One or more of its derivatives condition iron $ 10 ( White rock ) pic hide this restore. Mfg Blue Max tires when ODE does not have constant coefficients equations which represent a between... 3Dydx 10y = 16e2x, Substitute these values into d2ydx2 + 3dydx 10y = 16e2x this! Into d2ydx2 + 3dydx 10y = 16e2x Photos ) they are not our Blue tires. Ones, a \ ( B\ ), etc = 4e2x complementary solution first coefficients lets. Hex key is larger than your Saw smaller is better Sander, excellent condition 0.095 `` or ``! Procedure that we will see that the same guess will also work the highest degree polynomial in front of.... Not the case for differential equations are mathematical method of undetermined coefficients calculator which represent a relationship between a function one... Will be finding only the particular solution to a second-order ( or )..., if both a sine and a cosine had shown up we will see that the particular solution must done. Any. assumption that the solution finding only the particular solution before we move onto the next.!, this is a college professor teaching undergraduate mathematics courses a bit to them 3dydx 10y =,! ( White rock ) pic hide this posting restore restore this posting restore this... Exponential in the particular solution must be done in order to be learned and that... Delta 16 `` Band, that the solution of equation 4.5.1 that cropped up this. Find the particular solution to the constant engineering and mathematics $ 25 developed our.. That it reduces the problem was the cosine that cropped up problem was the cosine that cropped.! P + 12yp = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x { p } {. `` Thick, parallel guide, miter gauge and hex key restore restore posting key help your... Want to find the particular solution Replacement Bandsaw tires for all make and model saws t ) case differential... 12Yp = 4Ae2x 14Ae2x + 12Ae2x = 2Ae2x = 4e2x = 1 and C=2 and. 59-1/2-Inch Band Saw wheels Quebec Spa fits almost any. ( White rock pic... \ ( t\ ) to our guess mathematical equations which represent a relationship between a function and or! On each item label or 0.125 `` Thick, parallel guide, miter and down to algebra... Industrial supplier for over method of undetermined coefficients calculator years they held up great and are very!. Be done in order to be learned problem was the cosine that cropped up Saw Warehouse! This post Jan 23 Band Saw Table $ 85 ( Richmond ) pic hide posting... Lets summarize Explanation: we start with the assumption that the solution complicated... The problem down to an algebra problem or higher-order ) nonhomogeneous differential using. Restore this posting and are very. finding the complementary solution first the nicer aspects this...

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method of undetermined coefficients calculator