## Elementary Linear Algebra 7th Edition

(a) $\sin 3 x+\cos 3 x$ is a solution. (b) $3 \sin x+3 \cos x$ is not a solution. (c) $\sin 3x$ is a solution. (d) $\cos 3x$ is a solution.
(a) $\sin 3 x+\cos 3 x$ is a solution. (b) $3 \sin x+3 \cos x$ is not a solution. (c) $\sin 3x$ is a solution. (d) $\cos 3x$ is a solution.