If the domain of the function 5(18x - x2 - 77) is ( , ) and the domain of the function (x-1) ( 2x2 + 3x - 2x2 - 3x - 4 ) is ( , ), then 2 + 2 + 2 is equal to:
- 186
- 179
- 195
- 174
Answer
(1) 186
Solution
needs argument >0, base >0, base 1
First: 18x-x2-77>0 ⇒ (x-7)(x-11)<0 ⇒ (7,11) ⇒ =7, =11
Second: base x-1>0, 1 ⇒ x>1, x 2; (2x-1)(x+2)(x-4)(x+1)>0 — for x>1 only (x-4) can be negative ⇒ x>4 ⇒ =4
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∴ 2+ 2+ 2=49+121+16=186
Answer: (1)