Let f(x) = cos^-1 2x. Then, dom (f) = ?

Question

Mark (√) against the correct answer in the following:

Let f(x) = cos^-1 2x. Then, dom (f) = ?

A. [ - 1, 1]

B. \([\frac{-1}{2},\frac{1}{2}]\)

C. \([\frac{-\pi}{2},\frac{\pi}{2}]\)

D. \([\frac{-\pi}{4},\frac{\pi}{4}]\)

Answer 1

Correct Answer is (B) \([\frac{-1}{2},\frac{1}{2}]\)

f(x) = cos^-1 2x.

domain of cos^-1x = [ - 1,1]

on multiplying by an integer the domain decreases by same number

⇒ domain of cos^-1 2x = [-1/2, 1/2]