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Solve the inequality x2 + 2x > 15.

Solve the inequality x2 + 2x > 15.
  • A.
    x 5
  • B.
    -5
  • C.
    x 5
  • D.
    x > 3 or x
Correct Answer: Option D
Explanation

x2 + 2x > 15
x2 + 2x – 15 > 0
(x2 + 5x) – (3x – 15) > 0
x(x + 5) – 3(x + 5) >0
(x – 3)(x + 5) > 0
therefore, x = 3 or -5
then x 3
i.e. x