View Full Version : Initial value prob
Vi Nguyen
May 13, 2009, 12:04 AM
How do you solve an initial value problem:
dy/dx= xe^(y-x^2) and y(0) = 0
galactus
May 13, 2009, 02:36 PM
With this one, the best way is to separate variables:
\frac{dy}{dx}=xe^{y-x^{2}}
Rewrite using the log laws:
\frac{dy}{dx}=x\cdot\frac{e^{y}}{e^{x^{2}}
Separate variables:
\frac{dy}{e^{y}}=\frac{x}{e^{x^{2}}}dx
Integrate:
-e^{-y}=C-\frac{e^{-x^{2}}}{2}
Now, can you finish by using the initial condition and solving for C? Just set y=0 and x=0 and solve for C.
You can also solve for y.
Vi Nguyen
May 14, 2009, 04:06 AM
You're the best!! Spent ages trying to work this one out. I don't know how to rate the answer, so please excuse me if I don't somehow rate it.:D
With this one, the best way is to separate variables:
\frac{dy}{dx}=xe^{y-x^{2}}
Rewrite using the log laws:
\frac{dy}{dx}=x\cdot\frac{e^{y}}{e^{x^{2}}
Separate variables:
\frac{dy}{e^{y}}=\frac{x}{e^{x^{2}}}dx
Integrate:
-e^{-y}=C-\frac{e^{-x^{2}}}{2}
Now, can you finish by using the initial condition and solving for C?. Just set y=0 and x=0 and solve for C.
You can also solve for y.
galactus
May 14, 2009, 12:46 PM
To rate an answer, just click on 'Rate this Answer" directly below the post.
Glad I could help.
Cheers,
Cody