Solve Using the Quadratic Formula 3x^2-7x-9=0

$3 x^{2} - 7 x - 9 = 0$

Step 1

Use the quadratic formula to find the solutions.

$\frac{- b \pm \sqrt{b^{2} - 4 (a c)}}{2 a}$

Step 2

Substitute the values $a = 3$ , $b = - 7$ , and $c = - 9$ into the quadratic formula and solve for $x$ .

$\frac{7 \pm \sqrt{{(- 7)}^{2} - 4 \cdot (3 \cdot - 9)}}{2 \cdot 3}$

Step 3

Simplify.

Simplify the numerator.

Raise $- 7$ to the power of $2$ .

$x = \frac{7 \pm \sqrt{49 - 4 \cdot 3 \cdot - 9}}{2 \cdot 3}$

Multiply $- 4 \cdot 3 \cdot - 9$ .

Multiply $- 4$ by $3$ .

$x = \frac{7 \pm \sqrt{49 - 12 \cdot - 9}}{2 \cdot 3}$

Multiply $- 12$ by $- 9$ .

$x = \frac{7 \pm \sqrt{49 + 108}}{2 \cdot 3}$

Add $49$ and $108$ .

$x = \frac{7 \pm \sqrt{157}}{2 \cdot 3}$

Multiply $2$ by $3$ .

$x = \frac{7 \pm \sqrt{157}}{6}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$x = \frac{7 \pm \sqrt{157}}{6}$

Decimal Form:

$x = 3.25499401 \dots, - 0.92166068 \dots$