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