Ordinary Differential Equations/Non Homogenous 3

Solve

 * 1) $$y''-y=e^{-x},x\in\mathbb R, y(0)=y'(0)=0$$

Find Particular Integral

 * 1) $$y''-7y+12y=24e^x$$
 * 2) $$ y''+4y'+4y=e^{-2x}$$