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ExamsJEE MainMaths

Solve the inequality over the real numbers: ((x - 1)(x + 2)²) / (-1 - x) < 0.

  1. x in (-inf, -2) U (-2, -1) U (1, inf)
  2. x in (-1, 1)
  3. x in (-2, 1)
  4. x in (-inf, -1) U (1, inf), x != -2

Correct answer: x in (-inf, -2) U (-2, -1) U (1, inf)

Solution

The factor (x+2)² is non-negative and equals zero only at x = -2 (excluded since we need strict <0, but at x=-2 the expression is 0, not <0, so x=-2 is excluded). Rewriting: ((x-1)(x+2)²)/(-(x+1)) < 0 is equivalent to ((x-1)(x+2)²)/(x+1) > 0. Sign analysis of (x-1)/(x+1) (with (x+2)² > 0 for x != -2) gives the solution x < -1 or x > 1, excluding x = -2 where the expression is zero. So x in (-inf,-2) U (-2,-1) U (1, inf).

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