Answer
(a) ${x}e^{2x}$ is not a solution.
(b) $2 e^{2x}$ is a solution.
(c) $2 e^{-2x}$ is not a solution.
(d) $x e^{-x}$ is not a solution.
Work Step by Step
Consider the linear differential equation $y^{\prime \prime}-y^{\prime}-2 y=0$
(a) ${x}e^{2x}$ is not a solution.
(b) $2 e^{2x}$ is a solution.
(c) $2 e^{-2x}$ is not a solution.
(d) $x e^{-x}$ is not a solution.