The product of all possible values of , for which x 0 ( 1- ( x) (( +1)x) (( +2)x) 2(( +1)x) )=2, is :
- -2
- 1
- -1
- 54
Answer
(3) -1
Solution
For small x, (kx) = 1 - k2x22 + O (x4 ), so
( x) (( + 1)x) (( + 2)x) = 1 - [ 2 + ( + 1)2 + ( + 2)2 ]x22 + O (x4 )
and 2(( + 1)x) = ( + 1)2x2 + O (x4 ). Hence, for -1,
Limit = 2 + ( + 1)2 + ( + 2)22( + 1)2 = 2
3 2 + 6 + 5 = 4 2 + 8 + 4
2 + 2 - 1 = 0
Its roots -1 2 are real, distinct and neither equals -1.
∴ Product of all values of = -1
Answer: (3)