Precalculus Examples

${(x - 1)}^{2} + {(y + 4)}^{2} = 4$ , $y^{2} + 8 y - x + 13 = 0$

Step 1

Subtract ${(x - 1)}^{2}$ from both sides of the equation.

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

$y^{2} + 8 y - x + 13 = 0$

Step 2

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

$y + 4 = \pm \sqrt{4 - {(x - 1)}^{2}}$

$y^{2} + 8 y - x + 13 = 0$

Step 3

Simplify $\pm \sqrt{4 - {(x - 1)}^{2}}$ .

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Rewrite $4$ as $2^{2}$ .

$y + 4 = \pm \sqrt{2^{2} - {(x - 1)}^{2}}$

$y^{2} + 8 y - x + 13 = 0$

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 2$ and $b = x - 1$ .

$y + 4 = \pm \sqrt{(2 + x - 1) (2 - (x - 1))}$

$y^{2} + 8 y - x + 13 = 0$

Simplify.

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Subtract $1$ from $2$ .

$y + 4 = \pm \sqrt{(x + 1) (2 - (x - 1))}$

$y^{2} + 8 y - x + 13 = 0$

Apply the distributive property.

$y + 4 = \pm \sqrt{(x + 1) (2 - x + 1)}$

$y^{2} + 8 y - x + 13 = 0$

Multiply $- 1$ by $- 1$ .

$y + 4 = \pm \sqrt{(x + 1) (2 - x + 1)}$

$y^{2} + 8 y - x + 13 = 0$

Add $2$ and $1$ .

$y + 4 = \pm \sqrt{(x + 1) (- x + 3)}$

$y^{2} + 8 y - x + 13 = 0$

$y + 4 = \pm \sqrt{(x + 1) (- x + 3)}$

$y^{2} + 8 y - x + 13 = 0$

$y + 4 = \pm \sqrt{(x + 1) (- x + 3)}$

$y^{2} + 8 y - x + 13 = 0$

Step 4

The complete solution is the result of both the positive and negative portions of the solution.

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First, use the positive value of the $\pm$ to find the first solution.

$y + 4 = \sqrt{(x + 1) (- x + 3)}$

$y^{2} + 8 y - x + 13 = 0$

Subtract $4$ from both sides of the equation.

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y^{2} + 8 y - x + 13 = 0$

Next, use the negative value of the $\pm$ to find the second solution.

$y + 4 = - \sqrt{(x + 1) (- x + 3)}$

$y^{2} + 8 y - x + 13 = 0$

Subtract $4$ from both sides of the equation.

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y^{2} + 8 y - x + 13 = 0$

The complete solution is the result of both the positive and negative portions of the solution.

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y^{2} + 8 y - x + 13 = 0$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y^{2} + 8 y - x + 13 = 0$

Step 5

Use the quadratic formula to find the solutions.

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

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 6

Substitute the values $a = 1$ , $b = 8$ , and $c = - x + 13$ into the quadratic formula and solve for $y$ .

$\frac{- 8 \pm \sqrt{8^{2} - 4 \cdot (1 \cdot (- x + 13))}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 7

Simplify.

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Simplify the numerator.

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

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot 1 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $1$ .

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Apply the distributive property.

$y = \frac{- 8 \pm \sqrt{64 - 4 (- x) - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 1$ by $- 4$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $13$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 52}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Subtract $52$ from $64$ .

$y = \frac{- 8 \pm \sqrt{4 x + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 12$ .

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Factor $4$ out of $4 x$ .

$y = \frac{- 8 \pm \sqrt{4 (x) + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $12$ .

$y = \frac{- 8 \pm \sqrt{4 x + 4 \cdot 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 4 \cdot 3$ .

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Rewrite $4$ as $2^{2}$ .

$y = \frac{- 8 \pm \sqrt{2^{2} (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Pull terms out from under the radical.

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $2$ by $1$ .

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Simplify $\frac{- 8 \pm 2 \sqrt{x + 3}}{2}$ .

$y = - 4 \pm \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = - 4 \pm \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 8

Simplify the expression to solve for the $+$ portion of the $\pm$ .

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Simplify the numerator.

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

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot 1 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $1$ .

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Apply the distributive property.

$y = \frac{- 8 \pm \sqrt{64 - 4 (- x) - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 1$ by $- 4$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $13$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 52}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Subtract $52$ from $64$ .

$y = \frac{- 8 \pm \sqrt{4 x + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 12$ .

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Factor $4$ out of $4 x$ .

$y = \frac{- 8 \pm \sqrt{4 (x) + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $12$ .

$y = \frac{- 8 \pm \sqrt{4 x + 4 \cdot 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 4 \cdot 3$ .

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Rewrite $4$ as $2^{2}$ .

$y = \frac{- 8 \pm \sqrt{2^{2} (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Pull terms out from under the radical.

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $2$ by $1$ .

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Simplify $\frac{- 8 \pm 2 \sqrt{x + 3}}{2}$ .

$y = - 4 \pm \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Change the $\pm$ to $+$ .

$y = - 4 + \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = - 4 + \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 9

Simplify the expression to solve for the $-$ portion of the $\pm$ .

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Simplify the numerator.

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

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot 1 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $1$ .

$y = \frac{- 8 \pm \sqrt{64 - 4 \cdot (- x + 13)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Apply the distributive property.

$y = \frac{- 8 \pm \sqrt{64 - 4 (- x) - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 1$ by $- 4$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 4 \cdot 13}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $- 4$ by $13$ .

$y = \frac{- 8 \pm \sqrt{64 + 4 x - 52}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Subtract $52$ from $64$ .

$y = \frac{- 8 \pm \sqrt{4 x + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 12$ .

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Factor $4$ out of $4 x$ .

$y = \frac{- 8 \pm \sqrt{4 (x) + 12}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $12$ .

$y = \frac{- 8 \pm \sqrt{4 x + 4 \cdot 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Factor $4$ out of $4 x + 4 \cdot 3$ .

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm \sqrt{4 (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Rewrite $4$ as $2^{2}$ .

$y = \frac{- 8 \pm \sqrt{2^{2} (x + 3)}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Pull terms out from under the radical.

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2 \cdot 1}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Multiply $2$ by $1$ .

$y = \frac{- 8 \pm 2 \sqrt{x + 3}}{2}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Simplify $\frac{- 8 \pm 2 \sqrt{x + 3}}{2}$ .

$y = - 4 \pm \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Change the $\pm$ to $-$ .

$y = - 4 - \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

$y = - 4 - \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 10

The final answer is the combination of both solutions.

$y = - 4 + \sqrt{x + 3}$

$y = - 4 - \sqrt{x + 3}$

$y = \sqrt{(x + 1) (- x + 3)} - 4$

$y = - \sqrt{(x + 1) (- x + 3)} - 4$

Step 11

Create a graph to locate the intersection of the equations. The intersection of the system of equations is the solution.

$(1, - 2)$

$(1, - 6)$

$(0, - 4 + \sqrt{3})$

$(0, - 4 - \sqrt{3})$

Step 12