Solve Using the Quadratic Formula x^2+5x-8=0

$x^{2} + 5 x - 8 = 0$

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 $a = 1$ , $b = 5$ , and $c = - 8$ into the quadratic formula and solve for $x$ .

$\frac{- 5 \pm \sqrt{5^{2} - 4 \cdot (1 \cdot - 8)}}{2 \cdot 1}$

Step 3

Simplify.

Simplify the numerator.

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

$x = \frac{- 5 \pm \sqrt{25 - 4 \cdot 1 \cdot - 8}}{2 \cdot 1}$

Multiply $- 4 \cdot 1 \cdot - 8$ .

Multiply $- 4$ by $1$ .

$x = \frac{- 5 \pm \sqrt{25 - 4 \cdot - 8}}{2 \cdot 1}$

Multiply $- 4$ by $- 8$ .

$x = \frac{- 5 \pm \sqrt{25 + 32}}{2 \cdot 1}$

Add $25$ and $32$ .

$x = \frac{- 5 \pm \sqrt{57}}{2 \cdot 1}$

Multiply $2$ by $1$ .

$x = \frac{- 5 \pm \sqrt{57}}{2}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$x = \frac{- 5 \pm \sqrt{57}}{2}$

Decimal Form:

$x = 1.27491721 \dots, - 6.27491721 \dots$