Question

State True or False.

Let $f:R\to R$ be defined by $f\left(x\right)=cos(5x+2)$. Then $f$ is invertible.

• A. True
• B. False

Answer 1

The correct option is B False

$f\left(x\right)=\cos (5x+2)$

$x=[{\cos }^{-1}\left(f\left(x\right)\right)-2]\frac{1}{5}$

As, $-1\le f\left(x\right)\le 1$

So, we can't put other values which makes it INTO function.

So, $f\left(x\right)=cos(5x+2)$ is not invertible.