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 Differential Equations Ordinary and Partial Differential Equations Math Forum

 April 16th, 2015, 03:17 AM #1 Member   Joined: Apr 2014 From: australia Posts: 68 Thanks: 32 Ode Hi, just want to check if i have obtained the correct answer for the question below: dy/dt = 4y (x^3 - 1/2); a) Find ODE solution subject to initial conditions y(1) = 3/e. b) Find y(-1) Ans (a) For the general solution i get, y = Ce^(x^4 - 2x) At initial condition y(1) = 3/e y =3e^(x^4 - 2x) Ans (b) 3e thanks in advance Thanks from Yury Stepanyants April 16th, 2015, 03:33 AM   #2
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Quote:
 Originally Posted by harley05 Hi, just want to check if i have obtained the correct answer for the question below: dy/dt = 4y (x^3 - 1/2); a) Find ODE solution subject to initial conditions y(1) = 3/e. b) Find y(-1) Ans (a) For the general solution i get, y = Ce^(x^4 - 2x) At initial condition y(1) = 3/e y =3e^(x^4 - 2x) Ans (b) 3e thanks in advance
A question about your ODE: Is this supposed to be dy/dx = ... or is x a function of t as well?

-Dan

Edit: Yup. It's a typo. You have the correct solution, but look at y(-1) again. $\displaystyle y(-1) = 3 \cdot exp((-1)^4 - 2(-1)) = 3 \cdot exp(1 + 2) = 3e^3$.

-Dan

Last edited by topsquark; April 16th, 2015 at 03:38 AM. April 16th, 2015, 03:52 AM #3 Member   Joined: Apr 2014 From: australia Posts: 68 Thanks: 32 thanks, yes it was a typo as you noticed. thanks again. Thanks from Yury Stepanyants Tags ode Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

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