## Elementary Linear Algebra 7th Edition

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