Algebra Examples

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

Step 1

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

Tap for more steps...

Step 1.1

Subtract $x$ from both sides of the equation.

$y^{2} - 8 y - 5 = - x$

Step 1.2

Add $5$ to both sides of the equation.

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

Step 2

Complete the square.

Tap for more steps...

Step 2.1

Use the form $a x^{2} + b x + c$ , to find the values of $a$ , $b$ , and $c$ .

$a = 1$

$b = - 8$

$c = 0 = - x + 5$

Step 2.2

Consider the vertex form of a parabola.

$a {(x + d)}^{2} + e = - x + 5$

Step 2.3

Find the value of $d$ using the formula $d = \frac{b}{2 a}$ .

Tap for more steps...

Step 2.3.1

Substitute the values of $a$ and $b$ into the formula $d = \frac{b}{2 a}$ .

$d = \frac{- 8}{2 \cdot 1}$

Step 2.3.2

Cancel the common factor of $- 8$ and $2$ .

Tap for more steps...

Step 2.3.2.1

Factor $2$ out of $- 8$ .

$d = \frac{2 \cdot - 4}{2 \cdot 1}$

Step 2.3.2.2

Cancel the common factors.

Tap for more steps...

Step 2.3.2.2.1

Factor $2$ out of $2 \cdot 1$ .

$d = \frac{2 \cdot - 4}{2 (1)}$

Step 2.3.2.2.2

Cancel the common factor.

$d = \frac{2 \cdot - 4}{2 \cdot 1}$

Step 2.3.2.2.3

Rewrite the expression.

$d = \frac{- 4}{1}$

Step 2.3.2.2.4

Divide $- 4$ by $1$ .

$d = - 4$

Step 2.4

Find the value of $e$ using the formula $e = c - \frac{b^{2}}{4 a}$ .

Tap for more steps...

Step 2.4.1

Substitute the values of $c$ , $b$ and $a$ into the formula $e = c - \frac{b^{2}}{4 a}$ .

$e = 0 - \frac{{(- 8)}^{2}}{4 \cdot 1}$

Step 2.4.2

Simplify the right side.

Tap for more steps...

Step 2.4.2.1

Simplify each term.

Tap for more steps...

Step 2.4.2.1.1

Raise $- 8$ to the power of $2$ .

$e = 0 - \frac{64}{4 \cdot 1}$

Step 2.4.2.1.2

Multiply $4$ by $1$ .

$e = 0 - \frac{64}{4}$

Step 2.4.2.1.3

Divide $64$ by $4$ .

$e = 0 - 1 \cdot 16$

Step 2.4.2.1.4

Multiply $- 1$ by $16$ .

$e = 0 - 16$

Step 2.4.2.2

Subtract $16$ from $0$ .

$e = - 16$

Step 2.5

Substitute the values of $a$ , $d$ , and $e$ into the vertex form ${(y - 4)}^{2} - 16$ .

${(y - 4)}^{2} - 16 = - x + 5$

Step 3

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

Tap for more steps...

Step 3.1

Add $16$ to both sides of the equation.

${(y - 4)}^{2} = - x + 5 + 16$

Step 3.2

Add $5$ and $16$ .

${(y - 4)}^{2} = - x + 21$

Step 4

Factor.

Tap for more steps...

Step 4.1

Factor $- 1$ out of $- x$ .

${(y - 4)}^{2} = - (x) + 21$

Step 4.2

Rewrite $21$ as $- 1 (- 21)$ .

${(y - 4)}^{2} = - (x) - 1 (- 21)$

Step 4.3

Factor $- 1$ out of $- (x) - 1 (- 21)$ .

${(y - 4)}^{2} = - (x - 21)$