Solve Using the Quadratic Formula x^2+42=13x

$x^{2} + 42 = 13 x$

Step 1

Subtract $13 x$ from both sides of the equation.

$x^{2} + 42 - 13 x = 0$

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 $a = 1$ , $b = - 13$ , and $c = 42$ into the quadratic formula and solve for $x$ .

$\frac{13 \pm \sqrt{{(- 13)}^{2} - 4 \cdot (1 \cdot 42)}}{2 \cdot 1}$

Step 4

Simplify.

Simplify the numerator.

Raise $- 13$ to the power of $2$ .

$x = \frac{13 \pm \sqrt{169 - 4 \cdot 1 \cdot 42}}{2 \cdot 1}$

Multiply $- 4 \cdot 1 \cdot 42$ .

Multiply $- 4$ by $1$ .

$x = \frac{13 \pm \sqrt{169 - 4 \cdot 42}}{2 \cdot 1}$

Multiply $- 4$ by $42$ .

$x = \frac{13 \pm \sqrt{169 - 168}}{2 \cdot 1}$

Subtract $168$ from $169$ .

$x = \frac{13 \pm \sqrt{1}}{2 \cdot 1}$

Any root of $1$ is $1$ .

$x = \frac{13 \pm 1}{2 \cdot 1}$

Multiply $2$ by $1$ .

$x = \frac{13 \pm 1}{2}$

Step 5

The final answer is the combination of both solutions.

$x = 7, 6$