Solve the inequality x2 + 2x > 15.
A
x 5
B
-5 < x < 3
C
x 5
D
x > 3 or x < -5
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
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
i.e. x< 3 or x > -5
Source: WAEC / JAMB / NECO Classroom Archive (Record #29387)