If the domain of the function f(x) = -1 ( 2x - 511 - 3x ) + -1(2x2 - 3x + 1) is the interval [ , ], then + 2 is equal to :
- 5
- 2
- 3
- 1
Answer
(3) 3
Solution
For -1(2x2 - 3x + 1): -1 2x2 - 3x + 1 1
Right part: 2x2 - 3x 0 x(2x - 3) 0 0 x 32
Left part: 2x2 - 3x + 2 0, true for all real x (discriminant 9 - 16 < 0).
For -1 ( 2x - 511 - 3x ): -1 2x - 511 - 3x 1
For 0 x 32, 11 - 3x > 0, so
-(11 - 3x) 2x - 5 11 - 3x
x 6 and x 165, both true for every x [0, 32 ].
Domain = [0, 32 ]
= 0, = 32
+ 2 = 0 + 3 = 3
Answer: (3)