Basic Math Examples

$\frac{y^{3} - 8}{y^{2} + 6 y - 16} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 1

Simplify the numerator.

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Step 1.1

Rewrite $8$ as $2^{3}$ .

$\frac{y^{3} - 2^{3}}{y^{2} + 6 y - 16} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 1.2

Since both terms are perfect cubes, factor using the difference of cubes formula, $a^{3} - b^{3} = (a - b) (a^{2} + a b + b^{2})$ where $a = y$ and $b = 2$ .

$\frac{(y - 2) (y^{2} + y \cdot 2 + 2^{2})}{y^{2} + 6 y - 16} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 1.3

Simplify.

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Step 1.3.1

Move $2$ to the left of $y$ .

$\frac{(y - 2) (y^{2} + 2 \cdot y + 2^{2})}{y^{2} + 6 y - 16} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 1.3.2

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

$\frac{(y - 2) (y^{2} + 2 y + 4)}{y^{2} + 6 y - 16} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 2

Factor $y^{2} + 6 y - 16$ using the AC method.

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Step 2.1

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 16$ and whose sum is $6$ .

$- 2, 8$

Step 2.2

Write the factored form using these integers.

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y^{2} + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 3

Simplify terms.

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Step 3.1

Factor $y$ out of $y^{2} + 8 y$ .

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Step 3.1.1

Factor $y$ out of $y^{2}$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y \cdot y + 8 y}{y^{3} + 2 y^{2} + 4 y}$

Step 3.1.2

Factor $y$ out of $8 y$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y \cdot y + y \cdot 8}{y^{3} + 2 y^{2} + 4 y}$

Step 3.1.3

Factor $y$ out of $y \cdot y + y \cdot 8$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y^{3} + 2 y^{2} + 4 y}$

Step 3.2

Factor $y$ out of $y^{3} + 2 y^{2} + 4 y$ .

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Step 3.2.1

Factor $y$ out of $y^{3}$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y \cdot y^{2} + 2 y^{2} + 4 y}$

Step 3.2.2

Factor $y$ out of $2 y^{2}$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y \cdot y^{2} + y (2 y) + 4 y}$

Step 3.2.3

Factor $y$ out of $4 y$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y \cdot y^{2} + y (2 y) + y \cdot 4}$

Step 3.2.4

Factor $y$ out of $y \cdot y^{2} + y (2 y)$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y (y^{2} + 2 y) + y \cdot 4}$

Step 3.2.5

Factor $y$ out of $y (y^{2} + 2 y) + y \cdot 4$ .

$\frac{(y - 2) (y^{2} + 2 y + 4)}{(y - 2) (y + 8)} \cdot \frac{y (y + 8)}{y (y^{2} + 2 y + 4)}$

Step 3.3

Combine.

$\frac{(y - 2) (y^{2} + 2 y + 4) (y (y + 8))}{(y - 2) (y + 8) (y (y^{2} + 2 y + 4))}$

Step 3.4

Cancel the common factor of $y - 2$ .

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Step 3.4.1

Cancel the common factor.

$\frac{(y - 2) (y^{2} + 2 y + 4) (y (y + 8))}{(y - 2) (y + 8) (y (y^{2} + 2 y + 4))}$

Step 3.4.2

Rewrite the expression.

$\frac{(y^{2} + 2 y + 4) (y (y + 8))}{(y + 8) (y (y^{2} + 2 y + 4))}$

Step 3.5

Cancel the common factor of $y^{2} + 2 y + 4$ .

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Step 3.5.1

Cancel the common factor.

$\frac{(y^{2} + 2 y + 4) (y (y + 8))}{(y + 8) (y (y^{2} + 2 y + 4))}$

Step 3.5.2

Rewrite the expression.

$\frac{y (y + 8)}{(y + 8) (y)}$

Step 3.6

Cancel the common factor of $y$ .

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Step 3.6.1

Cancel the common factor.

$\frac{y (y + 8)}{(y + 8) y}$

Step 3.6.2

Rewrite the expression.

$\frac{y + 8}{y + 8}$

Step 3.7

Cancel the common factor of $y + 8$ .

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Step 3.7.1

Cancel the common factor.

$\frac{y + 8}{y + 8}$

Step 3.7.2

Rewrite the expression.

$1$