Finite Math Examples

$(\frac{\frac{25 k^{2} - 10 k - 24}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}}) \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1

Factor by grouping.

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Step 1.1

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = 25 \cdot - 24 = - 600$ and whose sum is $b = - 10$ .

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Step 1.1.1

Factor $- 10$ out of $- 10 k$ .

$\frac{\frac{25 k^{2} - 10 (k) - 24}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1.1.2

Rewrite $- 10$ as $20$ plus $- 30$

$\frac{\frac{25 k^{2} + (20 - 30) k - 24}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1.1.3

Apply the distributive property.

$\frac{\frac{25 k^{2} + 20 k - 30 k - 24}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1.2

Factor out the greatest common factor from each group.

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Step 1.2.1

Group the first two terms and the last two terms.

$\frac{\frac{(25 k^{2} + 20 k) - 30 k - 24}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1.2.2

Factor out the greatest common factor (GCF) from each group.

$\frac{\frac{5 k (5 k + 4) - 6 (5 k + 4)}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 1.3

Factor the polynomial by factoring out the greatest common factor, $5 k + 4$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k^{2} + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 2

Factor $k$ out of $k^{2} + 7 k$ .

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Step 2.1

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

$\frac{\frac{(5 k + 4) (5 k - 6)}{k \cdot k + 7 k}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 2.2

Factor $k$ out of $7 k$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k \cdot k + k \cdot 7}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 2.3

Factor $k$ out of $k \cdot k + k \cdot 7$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k^{3} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3

Simplify the denominator.

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Step 3.1

Factor $k$ out of $k^{3} + 4 k^{2} - 21 k$ .

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Step 3.1.1

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

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k \cdot k^{2} + 4 k^{2} - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3.1.2

Factor $k$ out of $4 k^{2}$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k \cdot k^{2} + k (4 k) - 21 k}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3.1.3

Factor $k$ out of $- 21 k$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k \cdot k^{2} + k (4 k) + k \cdot - 21}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3.1.4

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

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k^{2} + 4 k) + k \cdot - 21}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3.1.5

Factor $k$ out of $k (k^{2} + 4 k) + k \cdot - 21$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k^{2} + 4 k - 21)}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 3.2

Factor $k^{2} + 4 k - 21$ using the AC method.

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Step 3.2.1

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 $- 21$ and whose sum is $4$ .

$- 3, 7$

Step 3.2.2

Write the factored form using these integers.

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k ((k - 3) (k + 7))}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{k^{2} - 6 k + 8}{5 k^{2} - 16 k - 16}$

Step 4

Factor $k^{2} - 6 k + 8$ using the AC method.

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Step 4.1

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 $8$ and whose sum is $- 6$ .

$- 4, - 2$

Step 4.2

Write the factored form using these integers.

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{5 k^{2} - 16 k - 16}$

Step 5

Factor by grouping.

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Step 5.1

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = 5 \cdot - 16 = - 80$ and whose sum is $b = - 16$ .

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Step 5.1.1

Factor $- 16$ out of $- 16 k$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{5 k^{2} - 16 (k) - 16}$

Step 5.1.2

Rewrite $- 16$ as $4$ plus $- 20$

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{5 k^{2} + (4 - 20) k - 16}$

Step 5.1.3

Apply the distributive property.

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{5 k^{2} + 4 k - 20 k - 16}$

Step 5.2

Factor out the greatest common factor from each group.

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Step 5.2.1

Group the first two terms and the last two terms.

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{(5 k^{2} + 4 k) - 20 k - 16}$

Step 5.2.2

Factor out the greatest common factor (GCF) from each group.

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{k (5 k + 4) - 4 (5 k + 4)}$

Step 5.3

Factor the polynomial by factoring out the greatest common factor, $5 k + 4$ .

$\frac{\frac{(5 k + 4) (5 k - 6)}{k (k + 7)}}{\frac{5 k - 6}{k (k - 3) (k + 7)}} \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 6

Multiply the numerator by the reciprocal of the denominator.

$\frac{(5 k + 4) (5 k - 6)}{k (k + 7)} \cdot \frac{k (k - 3) (k + 7)}{5 k - 6} \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7

Reduce the expression by cancelling the common factors.

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Step 7.1

Cancel the common factor of $5 k - 6$ .

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Step 7.1.1

Factor $5 k - 6$ out of $(5 k + 4) (5 k - 6)$ .

$\frac{(5 k - 6) (5 k + 4)}{k (k + 7)} \cdot \frac{k (k - 3) (k + 7)}{5 k - 6} \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.1.2

Cancel the common factor.

$\frac{(5 k - 6) (5 k + 4)}{k (k + 7)} \cdot \frac{k (k - 3) (k + 7)}{5 k - 6} \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.1.3

Rewrite the expression.

$\frac{5 k + 4}{k (k + 7)} (k (k - 3) (k + 7)) \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.2

Cancel the common factor of $k (k + 7)$ .

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Step 7.2.1

Factor $k (k + 7)$ out of $k (k - 3) (k + 7)$ .

$\frac{5 k + 4}{k (k + 7)} (k (k + 7) (k - 3)) \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.2.2

Cancel the common factor.

$\frac{5 k + 4}{k (k + 7)} (k (k + 7) (k - 3)) \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.2.3

Rewrite the expression.

$(5 k + 4) (k - 3) \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.3

Cancel the common factor of $5 k + 4$ .

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Step 7.3.1

Cancel the common factor.

$(5 k + 4) (k - 3) \cdot \frac{(k - 4) (k - 2)}{(5 k + 4) (k - 4)}$

Step 7.3.2

Rewrite the expression.

$(k - 3) \cdot \frac{(k - 4) (k - 2)}{k - 4}$

Step 7.4

Cancel the common factor of $k - 4$ .

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Step 7.4.1

Cancel the common factor.

$(k - 3) \cdot \frac{(k - 4) (k - 2)}{k - 4}$

Step 7.4.2

Divide $k - 2$ by $1$ .

$(k - 3) \cdot (k - 2)$

Step 8

Expand $(k - 3) (k - 2)$ using the FOIL Method.

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Step 8.1

Apply the distributive property.

$k (k - 2) - 3 (k - 2)$

Step 8.2

Apply the distributive property.

$k \cdot k + k \cdot - 2 - 3 (k - 2)$

Step 8.3

Apply the distributive property.

$k \cdot k + k \cdot - 2 - 3 k - 3 \cdot - 2$

Step 9

Simplify and combine like terms.

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Step 9.1

Simplify each term.

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Step 9.1.1

Multiply $k$ by $k$ .

$k^{2} + k \cdot - 2 - 3 k - 3 \cdot - 2$

Step 9.1.2

Move $- 2$ to the left of $k$ .

$k^{2} - 2 \cdot k - 3 k - 3 \cdot - 2$

Step 9.1.3

Multiply $- 3$ by $- 2$ .

$k^{2} - 2 k - 3 k + 6$

Step 9.2

Subtract $3 k$ from $- 2 k$ .

$k^{2} - 5 k + 6$