Solve by Completing the Square x^2-10x-5=9

$x^{2} - 10 x - 5 = 9$

Step 1

Move all terms not containing $x$ to the right side of the equation.

Add $5$ to both sides of the equation.

$x^{2} - 10 x = 9 + 5$

Add $9$ and $5$ .

$x^{2} - 10 x = 14$

Step 2

To create a trinomial square on the left side of the equation, find a value that is equal to the square of half of $b$ .

${(\frac{b}{2})}^{2} = {(- 5)}^{2}$

Step 3

Add the term to each side of the equation.

$x^{2} - 10 x + {(- 5)}^{2} = 14 + {(- 5)}^{2}$

Step 4

Simplify the equation.

Simplify the left side.

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

$x^{2} - 10 x + 25 = 14 + {(- 5)}^{2}$

Simplify the right side.

Simplify $14 + {(- 5)}^{2}$ .

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

$x^{2} - 10 x + 25 = 14 + 25$

Add $14$ and $25$ .

$x^{2} - 10 x + 25 = 39$

Step 5

Factor the perfect trinomial square into ${(x - 5)}^{2}$ .

${(x - 5)}^{2} = 39$

Step 6

Solve the equation for $x$ .

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$x - 5 = \pm \sqrt{39}$

Add $5$ to both sides of the equation.

$x = \pm \sqrt{39} + 5$

Step 7

The result can be shown in multiple forms.

Exact Form:

$x = \pm \sqrt{39} + 5$

Decimal Form:

$x = 11.24499799 \dots, - 1.24499799 \dots$