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← JEE Main 2015 · 4 Apr · Shift 1
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JEE Main 2015 · 4 Apr · Shift 1, Mathematics question 76

The area (in sq. units) of the region described by {(x,y):y2≤2x and y≥4x−1}\{(x,y):y^2\le2x\text{ and }y\ge4x-1\} is :

Choose one option
Answer and worked solution

Official answer: D

The parabola x=y22x=\frac{y^2}2 and the line x=y+14x=\frac{y+1}4 meet at y=1y=1 and y=−12y=-\frac12. The region lies between them:
∫−1/21(y+14−y22)dy=[y28+y4−y36]−1/21=932.\int_{-1/2}^1\left(\frac{y+1}4-\frac{y^2}2\right)dy=\left[\frac{y^2}8+\frac y4-\frac{y^3}6\right]_{-1/2}^1=\frac9{32}.