The area of the region \(x, y): y2 4x, x<4, xy(x-1)(x-2)(x-3)(x-4)>0, x 3 \ is
- 323
- 163
- 83
- 643
Answer
(1) 323
Solution
Sign of y must equal the sign of h(x)= x(x-1)(x-2)(x-3)(x-4), 0<x<4
h>0 on (0,1) (2,3) ⇒ upper half (y>0); h<0 on (1,2) (3,4) ⇒ lower half (y<0)
[figure]
∵ the parabola is symmetric about the x-axis, each shaded strip = area of one half over that interval
Area = 04 2 x dx= 43 [x3/2 ]04= 323
Answer: (1)