The area (in square units) bounded by the curves y=x, 2y−x+3=0, x-axis, and lying in the first quadrant is
(A)36
(B)18
(C)427
(D)9✓ Correct
Answer: (D)
Solution
The curve y=x and the line 2y−x+3=0 meet where 2x=x−3; squaring gives x2−10x+9=0, so x=1 or x=9, with y=1 or y=3. Integrating along y from 0 to 3 is cleaner, the strip running from the parabola x=y2 to the line x=2y+3: Area=∫03[(2y+3)−y2]dy=[y2+3y−3y3]03=9+9−9=9 square units.
JEE Main · 2013 · 07 Apr 2013 · Offline · Single correct option