Let S= \(x,y) R R: x 0, y 0, y2 4x, y2 12-2x and 3y+ 8 x 5 8 \. If the area of the region S is 2, then is equal to
- 172
- 173
- 174
- 175
Answer
(2) 173
Solution
Find which right boundary is active and integrate along y.
y2=4x and y2=12-2x meet at x=2, y=2 2; the line 3y+2 2x=10 2 also passes through (2,2 2) and meets y=0 at x=5 (before the parabola's x=6).
Line: x=5- 3y2 2. (6- y22 )- (5- 3y2 2 )=- 12 (y-2 2 ) (y+ 1 2 ) 0 on [0,2 2], so the line is the right boundary.
Area = 02 2 (5- 3y2 2- y24 )dy=10 2-3 2- 4 23= 173 2.
= 173. Answer: (B)