# Solving Inhomogeneous equation

1. Feb 18, 2008

### darkspym7

1. The problem statement, all variables and given/known data
Solve the inhomogeneous equation y'' + 4y = 4 with y(0)=0 and y'(0)=0.

3. The attempt at a solution

let Y(t) = A, A being some constant
Y'(t) = 0
Y''(t) = 0

Y''(t)+4Y(t)=4
=> 4Y(t)=4
=> 4A=4
=> A=1
=> y(t)=1
But y(0)=0, so that cannot be correct.

Any tips?

2. Feb 18, 2008

### EnumaElish

It looks like y is not a constant function; but a variable function that satisfies y'' + 4y = 4 with y(0)=0 and y'(0)=0.

3. Feb 18, 2008

### darkspym7

Yeah, I saw that, but how could I go about solving it if the right hand side is constant?

4. Feb 18, 2008

### Rainbow Child

The function $y(t)=1$ is a particular solution. You have to add this to the general solution of the homogeneous equation. Can you find it?