Find the range of values of x for which \(2x^{2} + 7x - 15 > 0\).

A.

\(x < -\frac{3}{2}\) or \(x > 5\)

B.

\(x < -5\) or \(x > \frac{3}{2}\)

C.

\(-\frac{3}{2} < x < 5\)

D.

\(-5 < x < \frac{3}{2}\)

Correct answer is B

\(2x^{2} + 7x - 15 > 0 \implies 2x^{2} - 3x + 10x - 15 > 0\)

\(x(2x - 3) + 5(2x - 3) > 0\)

\((x + 5)(2x - 3) > 0\)

For their product to be positive, they are either both +ve or -ve.

\(x + 5 > 0 \implies x > -5\)

\(2x - 3 > 0 \implies 2x > 3\)

\(x > \frac{3}{2}\)

Check:

\(x > -5: x = -3\)

\(2(-3)^{2} + 7(-3) - 15 = 18 - 21 - 15 = -18 < 0\) (Not satisfied)

\(\therefore x < -5\)

\(x > \frac{3}{2}: x = 2\)

\(2(2^{2}) + 7(2) - 15 = 8 + 14 - 15 = 7 > 0\) (Satisfied)