Question

The function f(x) = cos^–1 x + x increases in the interval.

A. (1, ∞)

B. (–1, ∞)

C. (–∞, ∞)

D. (0, ∞)

Answer 1

Correct answer is C.

Formula:- The necessary and sufficient condition for differentiable function defined on (a, b) to be strictly increasing on (a, b) is that f’(x) > 0 for all x ∈ (a, b)

Given:-

f(x) = cos^–1 x + x