Specify whether the given function solves the given differential equation. Uustity youl answer.

a$.y=cosx$ and $y^{\text{'}\text{'}}+y=0$

b$.y=4x^2$ and $y^{\text{'}}-2y=-8x^2+8x$

c$.x=e^t-1$ and $x^{\text{'}\text{'}}+3x^{\text{'}}-4x=0$

d$.y=e^t(sin2t-cos2t)$ and $y^{\text{'}\text{'}}-2y^{\text{'}}-5y=0$