My Math Forum

My Math Forum (http://mymathforum.com/math-forums.php)
-   Differential Equations (http://mymathforum.com/differential-equations/)
-   -   Ode (http://mymathforum.com/differential-equations/52732-ode.html)

harley05 April 16th, 2015 03:17 AM

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

topsquark April 16th, 2015 03:33 AM

Quote:

Originally Posted by harley05 (Post 228821)
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

harley05 April 16th, 2015 03:52 AM

thanks, yes it was a typo as you noticed. thanks again.


All times are GMT -8. The time now is 07:30 PM.

Copyright © 2019 My Math Forum. All rights reserved.