Let the domain of the function f(x) = -1 ( 4x + 53x - 7 ) be [ , ] and the domain of g(x) = 2 (2 - 6 27(2x + 5) ) be ( , ). Then |7( + ) + 4( + )| is equal to .
Answer
96
Solution
For f: -1 4x + 53x - 7 1
4x + 53x - 7 - 1 0 x + 123x - 7 0 -12 x < 73
4x + 53x - 7 + 1 0 7x - 23x - 7 0 x 27 or x > 73
domain = [-12, 27 ], so + = -12 + 27 = - 827
For g: 2x + 5 > 0 x > - 52
and 2 - 6 27(2x + 5) > 0 27(2x + 5) < 13 2x + 5 < 27 13 = 3 x < -1
domain = (- 52, -1 ), so + = - 72
|7( + ) + 4( + )| = |-82 - 14| = 96
Answer: 96