JEE Main 2 September 2020, Shift 2, Maths Q72

Question 72 of 75 in this shift, Maths question 22 of 25.

y=\sum_{k=1}^{6} k\cos^{-1}\left\{\frac{3}{5}\cos kx-\frac{4}{5}\sin kx\right\}

, then

\frac{dy}{dx}

x=0

is ________.

Official answer

91.00

NTA final key (Sep 2020).

Chapter: Continuity and Differentiability
Topic: Chain Rule
Idea tested: Pre-simplification via Trig Substitution

Same idea in other shifts

Asked 2× in all

17 Mar 2021, Shift 1 · Q89If $f(x)=\sin\left(\cos^{-1}\left(\frac{1-2^{2x}}{1+2^{2x}}\right)\right)$ and its first derivative with respect to $x$ is…HardNumerical value

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.