Solve Using the Quadratic Formula 2x^2+18x=20

$2 x^{2} + 18 x = 20$

Step 1

Subtract $20$ from both sides of the equation.

$2 x^{2} + 18 x - 20 = 0$

Step 2

Use the quadratic formula to find the solutions.

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

Step 3

Substitute the values $a = 2$ , $b = 18$ , and $c = - 20$ into the quadratic formula and solve for $x$ .

$\frac{- 18 \pm \sqrt{18^{2} - 4 \cdot (2 \cdot - 20)}}{2 \cdot 2}$

Step 4

Simplify.

Simplify the numerator.

Raise $18$ to the power of $2$ .

$x = \frac{- 18 \pm \sqrt{324 - 4 \cdot 2 \cdot - 20}}{2 \cdot 2}$

Multiply $- 4 \cdot 2 \cdot - 20$ .

Multiply $- 4$ by $2$ .

$x = \frac{- 18 \pm \sqrt{324 - 8 \cdot - 20}}{2 \cdot 2}$

Multiply $- 8$ by $- 20$ .

$x = \frac{- 18 \pm \sqrt{324 + 160}}{2 \cdot 2}$

Add $324$ and $160$ .

$x = \frac{- 18 \pm \sqrt{484}}{2 \cdot 2}$

Rewrite $484$ as $22^{2}$ .

$x = \frac{- 18 \pm \sqrt{22^{2}}}{2 \cdot 2}$

Pull terms out from under the radical, assuming positive real numbers.

$x = \frac{- 18 \pm 22}{2 \cdot 2}$

Multiply $2$ by $2$ .

$x = \frac{- 18 \pm 22}{4}$

Simplify $\frac{- 18 \pm 22}{4}$ .

$x = \frac{- 9 \pm 11}{2}$

Step 5

The final answer is the combination of both solutions.

$x = 1, - 10$