Questions in diff-equation

Select	Question
	If $\frac{{{d}^{2}}y}{d{{x}^{2}}}=0,$ then
	If $\frac{{{d}^{2}}y}{d{{x}^{2}}}+\sin x=0,$ then solution of the differential equation is.
	The solution of the equation $\frac{{{d}^{2}}y}{d{{x}^{2}}}={{e}^{-2x}}$ is