Question

f(x) = x/(x² - 1) is increasing in

A. (-1, 1)

B. (-1, ∞)

C. (-∞, -1) ∪ (1, ∞)

D. none of these

Answer 1

Answer is : A. (-1, 1)

⇒ For critical points f’(x) = 0

When f’(x) = 0

We get x = 1 or x = -1

When we plot them on number line as f’(x) is multiplied by –ve sign we get

For x > 1 function is decreasing

For x < -1 function is decreasing

But between -1 to 1 function is increasing.

∴ Function is increasing in (-1,1).