Mathematics · Area under the Curves

JEE Main 2025 — 28 January, Evening Shift — Question 9

The area of the region bounded by the curves x(1+y2)=1\mathrm{x}\left(1+\mathrm{y}^{2}\right)=1 and y2=2x\mathrm{y}^{2}=2 \mathrm{x} is :

  1. Option A:

    2(π2−13)2\left(\frac{\pi}{2}-\frac{1}{3}\right)

  2. Option B:

    π4−13\frac{\pi}{4}-\frac{1}{3}

  3. Option C:

    π2−13\frac{\pi}{2}-\frac{1}{3}

    Correct
  4. Option D:

    12(π2−13)\frac{1}{2}\left(\frac{\pi}{2}-\frac{1}{3}\right)

Answer: C

Step-by-step solution

x(1+y2)=1..(1)\mathrm{x}\left(1+\mathrm{y}^{2}\right)=1..(1)

y2=2x…(2)y^{2}=2 x…(2)

From equation (1) & (2)

x(1+2x)=1⇒2x2+x−1=0\mathrm{x}(1+2 \mathrm{x})=1 \Rightarrow 2 \mathrm{x}^{2}+\mathrm{x}-1=0

⇒x=12,x=−1\Rightarrow \mathrm{x}=\frac{1}{2}, \mathrm{x}=-1 (Reject)

⇒y2=2(12)\Rightarrow \mathrm{y}^{2}=2\left(\frac{1}{2}\right)

⇒y=±1\Rightarrow \mathrm{y}= \pm 1

 Area bounded =∫−11(11+y2−y22)dy=(tan⁡−1y−y36)∣−11=π2−13\begin{aligned} \text { Area bounded } & =\int_{-1}^{1}\left(\frac{1}{1+y^{2}}-\frac{y^{2}}{2}\right) d y \\& =\left.\left(\tan ^{-1} y-\frac{y^{3}}{6}\right)\right|_{-1} ^{1} \\& =\frac{\pi}{2}-\frac{1}{3} \end{aligned}
Solution figure

Answer key and solution verified before publishing.

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Exam
JEE Main 2025
Subject
Mathematics
Chapter
Area under the Curves
Topic
Area under the Curves