# How do you solve 3x^2 - 15x + 18 = 0  using the quadratic formula?

Jul 10, 2016

The answers are $x = 2 , 3$.

#### Explanation:

The quadratic formula is:

$x = \frac{- b \pm \sqrt{{b}^{2} - 4 a c}}{2} a$

And in your polynomial:
$a = 3$
$b = - 15$
$c = 18$

So plugging those in we get:

$x = \frac{15 \pm \sqrt{{15}^{2} - 4 \cdot 3 \cdot 18}}{2 \cdot 3}$
$= \frac{15 \pm \sqrt{225 - 216}}{6}$
$= \frac{15 \pm \sqrt{9}}{6}$
$= \frac{15 \pm 3}{6}$

So our two answers are:

$x = \frac{15 - 3}{6} = \frac{12}{6} = 2$
and
$x = \frac{15 + 3}{6} = \frac{18}{6} = 3$