Answer
$x = \dfrac{9 ± \sqrt {21}}{2}$
Work Step by Step
We are asked to solve this equation using the quadratic formula, which is given by:
$x = \dfrac{-b \pm \sqrt {b^2 - 4ac}}{2a}$
where $a$ is the coefficient of the first term, $b$ is the coefficient of the 1st degree term, and $c$ is the constant.
Let's plug in the numbers from our equation into the formula:
$x = \dfrac{-(-9) \pm \sqrt {(-9)^2 - 4(1)(15)}}{2(1)}$
Let's simplify:
$x = \dfrac{9 \pm \sqrt {81 - 60}}{2}$
Let's simplify what is inside the radical:
$x = \dfrac{9 \pm \sqrt {21}}{2}$
