). Solve the following two initial value equations. \text { (a) } y^{\prime \prime}+3 y^{\prime}+2 y=1+e^{-x} ; \quad y(0)=0, y^{\prime}(0)=1 \text { . } \text { (b) } y^{\prime \prime}+9

y=\cos ^{2} x ; \quad y(0)=1, y^{\prime}(0)=0 \text { . }