# Homework Help: Differential Equations initial value problem

1. Sep 30, 2010

### hocuspocus102

1. The problem statement, all variables and given/known data

Let f(t) be the solution to the initial value problem 2t(dy/dt)+y=t^4
with f(0) = 0
find f(t).

2. Relevant equations

3. The attempt at a solution

I tried to do this by separating variables but that hasn't gotten me very far. I don't know if I can do it by doing that thing where you find an integrating factor and like raising e^(some integral)? It didn't really make any sense to me when I tried it, so could someone explain it please? Thanks!

2. Sep 30, 2010

Or a cleaver substitution? Something of the form $$t^\alpha y$$ with some handy value of $$\alpha$$? Does not the left hand side of your equation look like a derivative of a something?

Last edited: Sep 30, 2010
3. Sep 30, 2010

### HallsofIvy

Because it is a linear equation, there is a formula for the "integrating factor". Write it as $dy/dx+ y/2t= (1/2)t^3$.

Now look for u(t) such that $d(uy)/dt= u (dy/dt)+ (du/dt)y= u dy/dt+ (u/2t)y$

Last edited by a moderator: Sep 30, 2010