Solve Using the Quadratic Formula 9x^2-5x-1=0

$9 x^{2} - 5 x - 1 = 0$

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 $a = 9$ , $b = - 5$ , and $c = - 1$ into the quadratic formula and solve for $x$ .

$\frac{5 \pm \sqrt{{(- 5)}^{2} - 4 \cdot (9 \cdot - 1)}}{2 \cdot 9}$

Step 3

Simplify.

Simplify the numerator.

Raise $- 5$ to the power of $2$ .

$x = \frac{5 \pm \sqrt{25 - 4 \cdot 9 \cdot - 1}}{2 \cdot 9}$

Multiply $- 4 \cdot 9 \cdot - 1$ .

Multiply $- 4$ by $9$ .

$x = \frac{5 \pm \sqrt{25 - 36 \cdot - 1}}{2 \cdot 9}$

Multiply $- 36$ by $- 1$ .

$x = \frac{5 \pm \sqrt{25 + 36}}{2 \cdot 9}$

Add $25$ and $36$ .

$x = \frac{5 \pm \sqrt{61}}{2 \cdot 9}$

Multiply $2$ by $9$ .

$x = \frac{5 \pm \sqrt{61}}{18}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$x = \frac{5 \pm \sqrt{61}}{18}$

Decimal Form:

$x = 0.71168053 \dots, - 0.15612498 \dots$