Question

Find the intervals in which f(x) = 2x^2 – 3x is increasing.

(a) (-1/4, ∞)

(b) (-3/4, ∞)

(c) (1/4, ∞)

(d) (3/4, ∞)

The question was asked during a job interview.

My question is from Derivatives Application in section Application of Derivatives of Mathematics – Class 12

Answer 1

Correct choice is (d) (3/4, ∞)

For explanation: f(x) = 2x^2-3x.

f’(x) = 4x – 3.

As we know f’(x) = 0, x=-3/4. This shows that function f is increasing in interval (-3/4, ∞) for all x ∈ R.