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JEE Main 2021 · MathsMultiple choiceSingle correctMediumApplication

JEE Main 22 July 2021, Shift 2, Maths Q75

Question 75 of 90 in this shift, Maths question 15 of 30, Section A.

Let

f:\mathbf{R}\to\mathbf{R}

be defined as

f(x)=\begin{cases}-\frac{4}{3}x^3+2x^2+3x, & x>0\\ 3xe^x, & x\leq0\end{cases}

Then

f

is increasing function in the interval.

(1) $\left(-\frac{1}{2}, 2\right)$
(2) $(-3, -1)$
(3) $\left(-1, \frac{3}{2}\right)$ Official answer
(4) $(0, 2)$

Official answer

Option 3

NTA final key.

Chapter: Application of Derivatives
Topic: Monotonicity
Idea tested: Monotonicity in Piecewise Functions

Same idea in other shifts

Asked 2× in all

24 Feb 2021, Shift 2 · Q73Let $f:\mathbf{R}\to\mathbf{R}$ be defined as…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.