Precalculus Examples

$\frac{\frac{r}{s} + \frac{s}{r}}{\frac{r^{2}}{s^{2}} - \frac{s^{2}}{r^{2}}}$

Step 1

Multiply the numerator and denominator of the fraction by $r^{2} s^{2}$ .

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Step 1.1

Multiply $\frac{\frac{r}{s} + \frac{s}{r}}{\frac{r^{2}}{s^{2}} - \frac{s^{2}}{r^{2}}}$ by $\frac{r^{2} s^{2}}{r^{2} s^{2}}$ .

$\frac{r^{2} s^{2}}{r^{2} s^{2}} \cdot \frac{\frac{r}{s} + \frac{s}{r}}{\frac{r^{2}}{s^{2}} - \frac{s^{2}}{r^{2}}}$

Step 1.2

Combine.

$\frac{r^{2} s^{2} (\frac{r}{s} + \frac{s}{r})}{r^{2} s^{2} (\frac{r^{2}}{s^{2}} - \frac{s^{2}}{r^{2}})}$

Step 2

Apply the distributive property.

$\frac{r^{2} s^{2} \frac{r}{s} + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3

Simplify by cancelling.

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Step 3.1

Cancel the common factor of $s$ .

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Step 3.1.1

Factor $s$ out of $r^{2} s^{2}$ .

$\frac{s (r^{2} s) \frac{r}{s} + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.1.2

Cancel the common factor.

$\frac{s (r^{2} s) \frac{r}{s} + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.1.3

Rewrite the expression.

$\frac{r^{2} s r + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.2

Raise $r$ to the power of $1$ .

$\frac{r^{1} r^{2} s + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{r^{1 + 2} s + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.4

Add $1$ and $2$ .

$\frac{r^{3} s + r^{2} s^{2} \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.5

Cancel the common factor of $r$ .

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Step 3.5.1

Factor $r$ out of $r^{2} s^{2}$ .

$\frac{r^{3} s + r (r s^{2}) \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.5.2

Cancel the common factor.

$\frac{r^{3} s + r (r s^{2}) \frac{s}{r}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.5.3

Rewrite the expression.

$\frac{r^{3} s + r s^{2} s}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.6

Raise $s$ to the power of $1$ .

$\frac{r^{3} s + r (s^{1} s^{2})}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.7

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{r^{3} s + r s^{1 + 2}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.8

Add $1$ and $2$ .

$\frac{r^{3} s + r s^{3}}{r^{2} s^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.9

Cancel the common factor of $s^{2}$ .

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Step 3.9.1

Factor $s^{2}$ out of $r^{2} s^{2}$ .

$\frac{r^{3} s + r s^{3}}{s^{2} r^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.9.2

Cancel the common factor.

$\frac{r^{3} s + r s^{3}}{s^{2} r^{2} \frac{r^{2}}{s^{2}} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.9.3

Rewrite the expression.

$\frac{r^{3} s + r s^{3}}{r^{2} r^{2} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.10

Multiply $r^{2}$ by $r^{2}$ by adding the exponents.

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Step 3.10.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{r^{3} s + r s^{3}}{r^{2 + 2} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.10.2

Add $2$ and $2$ .

$\frac{r^{3} s + r s^{3}}{r^{4} + r^{2} s^{2} (- \frac{s^{2}}{r^{2}})}$

Step 3.11

Cancel the common factor of $r^{2}$ .

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Step 3.11.1

Move the leading negative in $- \frac{s^{2}}{r^{2}}$ into the numerator.

$\frac{r^{3} s + r s^{3}}{r^{4} + r^{2} s^{2} \frac{- s^{2}}{r^{2}}}$

Step 3.11.2

Factor $r^{2}$ out of $r^{2} s^{2}$ .

$\frac{r^{3} s + r s^{3}}{r^{4} + r^{2} (s^{2}) \frac{- s^{2}}{r^{2}}}$

Step 3.11.3

Cancel the common factor.

$\frac{r^{3} s + r s^{3}}{r^{4} + r^{2} s^{2} \frac{- s^{2}}{r^{2}}}$

Step 3.11.4

Rewrite the expression.

$\frac{r^{3} s + r s^{3}}{r^{4} + s^{2} (- s^{2})}$

Step 3.12

Multiply $s^{2}$ by $s^{2}$ by adding the exponents.

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Step 3.12.1

Move $s^{2}$ .

$\frac{r^{3} s + r s^{3}}{r^{4} + s^{2} s^{2} \cdot - 1}$

Step 3.12.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{r^{3} s + r s^{3}}{r^{4} + s^{2 + 2} \cdot - 1}$

Step 3.12.3

Add $2$ and $2$ .

$\frac{r^{3} s + r s^{3}}{r^{4} + s^{4} \cdot - 1}$

Step 4

Factor $r s$ out of $r^{3} s + r s^{3}$ .

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Step 4.1

Factor $r s$ out of $r^{3} s$ .

$\frac{r s (r^{2}) + r s^{3}}{r^{4} + s^{4} \cdot - 1}$

Step 4.2

Factor $r s$ out of $r s^{3}$ .

$\frac{r s (r^{2}) + r s (s^{2})}{r^{4} + s^{4} \cdot - 1}$

Step 4.3

Factor $r s$ out of $r s (r^{2}) + r s (s^{2})$ .

$\frac{r s (r^{2} + s^{2})}{r^{4} + s^{4} \cdot - 1}$

Step 5

Simplify the denominator.

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Step 5.1

Rewrite $r^{4}$ as ${(r^{2})}^{2}$ .

$\frac{r s (r^{2} + s^{2})}{{(r^{2})}^{2} + s^{4} \cdot - 1}$

Step 5.2

Rewrite $s^{4}$ as ${(s^{2})}^{2}$ .

$\frac{r s (r^{2} + s^{2})}{{(r^{2})}^{2} - {(s^{2})}^{2}}$

Step 5.3

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

$\frac{r s (r^{2} + s^{2})}{(r^{2} + s^{2}) (r^{2} - s^{2})}$

Step 5.4

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

$\frac{r s (r^{2} + s^{2})}{(r^{2} + s^{2}) (r + s) (r - s)}$

Step 6

Cancel the common factor of $r^{2} + s^{2}$ .

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Step 6.1

Cancel the common factor.

$\frac{r s (r^{2} + s^{2})}{(r^{2} + s^{2}) (r + s) (r - s)}$

Step 6.2

Rewrite the expression.

$\frac{r s}{(r + s) (r - s)}$