Mathematics · JEE | APPLICATION OF DERIVATIVES
हिन्दीGiven below two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The function \( f(x) = x^3 - 3x^2 + 3x - 100 \) is strictly increasing on \( \mathbb{R} \). Reason (R): If \( f'(x) > 0 \) for all \( x \in \mathbb{R} \), then \( f(x) \) is strictly increasing on \( \mathbb{R} \). In the light of the above statements, choose the correct answer from the options given below:
View Answer & Solution
Correct answer · Option A
Both (A) and (R) are true and (R) is the correct explanation of (A).
Explanation
Here \( f'(x) = 3x^2 - 6x + 3 = 3(x-1)^2 \ge 0 \). Strictly speaking, since \( f'(x) > 0 \) for \( x \neq 1 \) and zero at \( x=1 \), it is strictly increasing on \( \mathbb{R} \). Both assertion and reason correctly apply.