Question

Find the roots of the quadratic equation $3x^2-5x-12=0$ by using the quadratic formula.

• A. $-\frac{2}{3},3$
• B. $-\frac{4}{3},-3$
• C. $-\frac{-4}{3},-3$
• D. $-\frac{4}{3},3$

Answer 1

The correct option is D $-\frac{4}{3},3$

Given:

$3x^2-5x-12=0$

$x=\frac{5\pm \sqrt{(-5{)}^2-(4\left)\right(3\left)\right(-12)}}{2\left(3\right)}$

$x=\frac{5\pm \sqrt{25+144}}{6}$

$x=\frac{5\pm \sqrt{169}}{6}$

$x=\frac{5\pm 13}{6}$

$x=\frac{5+13}{6}$ and $x=\frac{5-13}{6}$

$x=3$ and $x=\frac{-4}{3}$