Show that the equation is not an identity by finding a value of x for which both sides are defined but not equal.
-$\sin 2 x + \sin 4 x = \sin 5 x$
A) $\frac { \pi } { 2 }$
B) 0
C) $\pi$
D) $2 \pi$

Question

Quizplus · Accepted Answer

The equation is not an identity because $\sin 2x + \sin 4x$ is not equal to $\sin 5x$ for all values of $x$. For example, when $x = \frac{\pi}{2}$, $\sin 2x + \sin 4x = 0$, but $\sin 5x = 1$.

Show That the Equation Is Not an Identity by Finding sin⁡2x+sin⁡4x=sin⁡5x\sin 2 x + \sin 4 x = \sin 5 xsin2x+sin4x=sin5x

Show That the Equation Is Not an Identity by Finding $\sin 2 x + \sin 4 x = \sin 5 x$