massi2884 wrote:Is |x| < 1 ?
1) |x + 1| = 2|x - 1|
2) |x - 3| ≠0
OA C
Question is: Is |x| < 1 OR is -1 < x < 1 true?
(1) |x + 1| = 2|x - 1|
Square both sides, (x + 1)² = 4(x - 1)² or x² + 2x + 1 = 4x² - 8x + 4 or 3x² - 10x + 3 = 0 or x = 1/3 or x = 3.
So, two valid values of x are 1/3 and 3, from which 1/3 lies in the range -1 < x < 1 but 3 does not lies in this range; NOT sufficient.
(2) |x - 3| ≠0 or x ≠3 but we have no clue whether x is in the range (-1, 1) or not; NOT sufficient.
Combining (1) and (2), x = 1/3, or x = 3 and x ≠3 implies x can have only one value, that is, 1/3, which is in the range (-1,1); SUFFICIENT.
The correct answer is
C.