Mathematics · Differential Equations

JEE Main 2026 — 4 April, Morning Shift — Question 42

Let y = y(x) be the solution of the differential equation dydx=(1+x+x2)(1−y+y2)\frac{dy}{dx} = (1+x+x^2)(1-y+y^2), y(0)=1/2.y(0)=1/2. Then (2y(1)−1)(2y(1)-1) is equal to :

  1. Option A:

    3tan⁡(1136)3\tan\left(\frac{11\sqrt{3}}{6}\right)

  2. Option B:

    32tan⁡(11312)\frac{3}{2}\tan\left(\frac{11\sqrt{3}}{12}\right)

  3. Option C:

    3tan⁡(11312)\sqrt3\tan\left(\frac{11\sqrt{3}}{12}\right)

    Correct
  4. Option D:

    32tan⁡(1136)\frac{3}{2}\tan\left(\frac{11\sqrt{3}}{6}\right)

Answer: C

Step-by-step solution

dyy2−y+1=(x2+x+1)dx\frac{d y}{y^{2}-y+1}=\left(x^{2}+x+1\right) d x dy(y−12)2+(32)2=(x2+x+1)dx\frac{d y}{\left(y-\frac{1}{2}\right)^{2}+\left(\frac{\sqrt{3}}{2}\right)^{2}}=\left(x^{2}+x+1\right) d x 23tan⁡−1(y−1232)=x33+x32+x+C\frac{2}{\sqrt{3}} \tan ^{-1}\left(\frac{y-\frac{1}{2}}{\frac{\sqrt{3}}{2}}\right)=\frac{x^{3}}{3}+\frac{x^{3}}{2}+x+C 233=tan⁡−1(2y−13)=x33+x32+x+C\frac{2}{\sqrt{3 \sqrt{3}}}=\tan ^{-1}\left(\frac{2 y-1}{\sqrt{3}}\right)=\frac{x^{3}}{3}+\frac{x^{3}}{2}+x+C y(0)=12⇒0=0+0+0+C⇒C=0y(0)=\frac{1}{2} \Rightarrow 0=0+0+0+C \Rightarrow C=0 23tan⁡−1(2y−13)=x33+x22+x\frac{2}{\sqrt{3}} \tan ^{-1}\left(\frac{2 y-1}{\sqrt{3}}\right)=\frac{x^{3}}{3}+\frac{x^{2}}{2}+x put x=1\mathrm{x}=1 23tan⁡−1(2y−13)=13+12+1=2+3+66=116\frac{2}{\sqrt{3}} \tan ^{-1}\left(\frac{2 \mathrm{y}-1}{\sqrt{3}}\right)=\frac{1}{3}+\frac{1}{2}+1=\frac{2+3+6}{6}=\frac{11}{6} tan⁡−1(2y−13)=11312\tan ^{-1}\left(\frac{2 y-1}{\sqrt{3}}\right)=\frac{11 \sqrt{3}}{12} 2y−13=tan⁡(11312)\frac{2 y-1}{\sqrt{3}}=\tan \left(\frac{11 \sqrt{3}}{12}\right) ⇒2y(1)−1=3tan⁡(11312)\Rightarrow 2 y(1)-1=\sqrt{3} \tan \left(\frac{11 \sqrt{3}}{12}\right)

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Differential Equations
Topic
Methods of solving a First Order,First Degree Differential