If the domain of the function f(x) = 1 10 + 3x - x2 + 1 x + |x| is (a, b), then (1 + a)2 + b2 is equal to :
- 29
- 30
- 25
- 26
Answer
(4) 26
Solution
10 + 3x - x2 > 0 x2 - 3x - 10 < 0
(x - 5)(x + 2) < 0 -2 < x < 5
Also x + |x| > 0: for x 0, x + |x| = 0, while for x > 0, x + |x| = 2x > 0, so x > 0.
Hence the domain is (0, 5), i.e. a = 0, b = 5.
(1 + a)2 + b2 = 1 + 25 = 26
Answer: (4)