The area of the region bounded by the curves x(1 + y2) = 1 and y2 = 2x is:
- 4 - 13
- 2 - 13
- 2 ( 2 - 13 )
- 12 ( 2 - 13 )
Answer
(2) 2 - 13
Solution
Points of intersection: put x = y22 in x(1 + y2) = 1
y22(1 + y2) = 1
y4 + y2 - 2 = 0
(y2 + 2)(y2 - 1) = 0 y = 1, x = 12
[figure]
For -1 y 1 the region lies between x = y22 (left) and x = 11 + y2 (right), and it is symmetric about the x-axis.
A = -11 ( 11 + y2 - y22 )dy
= 2 01 ( 11 + y2 - y22 )dy
= 2 [ -1y - y36 ]01
= 2 ( 4 - 16 )
= 2 - 13
Answer: (2)