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Saturday, 31 October

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JEE Main 2021 · MathsMultiple choiceSingle correctHardMulti-step

JEE Main 31 August 2021, Shift 2, Maths Q71

Question 71 of 90 in this shift, Maths question 11 of 30, Section A.

If

y\frac{\mathrm{d}y}{\mathrm{d}x} = x\left[\frac{y^2}{x^2} + \frac{\phi\left(\frac{y^2}{x^2}\right)}{\phi'\left(\frac{y^2}{x^2}\right)}\right]

,

x > 0

,

\phi > 0

, and

y(1) = -1

, then

\phi\left(\frac{y^2}{4}\right)

is equal to :

(1) $\phi(1)$
(2) $2\phi(1)$
(3) $4\phi(1)$ Official answer
(4) $4\phi(2)$

Official answer

Option 3

NTA final key.

Chapter: Differential Equations
Topic: Homogeneous Equations
Idea tested: Homogeneous Equations with Transcendental Functions

Same idea in other shifts

Asked 2× in all

30 Jul 2022, Shift 2 · Q73If $y = y(x)$ satisfies the differential equation $x\,dy + \left(x \tan\left(\frac{y}{x}\right) - y\right) dx = 0$ , $x > 0$ , and…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.