Pre-Algebra Examples

$\frac{\frac{4 k^{2} - 3 k - 1}{4 k^{2} + 11 k + 7}}{\frac{16 k^{2} - 1}{4 k^{2} + 3 k - 7}}$

Step 1

Multiply the numerator by the reciprocal of the denominator.

$\frac{4 k^{2} - 3 k - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2

Factor by grouping.

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Step 2.1

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 $a \cdot c = 4 \cdot - 1 = - 4$ and whose sum is $b = - 3$ .

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Step 2.1.1

Factor $- 3$ out of $- 3 k$ .

$\frac{4 k^{2} - 3 (k) - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.1.2

Rewrite $- 3$ as $1$ plus $- 4$

$\frac{4 k^{2} + (1 - 4) k - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.1.3

Apply the distributive property.

$\frac{4 k^{2} + 1 k - 4 k - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.1.4

Multiply $k$ by $1$ .

$\frac{4 k^{2} + k - 4 k - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.2

Factor out the greatest common factor from each group.

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Step 2.2.1

Group the first two terms and the last two terms.

$\frac{(4 k^{2} + k) - 4 k - 1}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.2.2

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

$\frac{k (4 k + 1) - (4 k + 1)}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 2.3

Factor the polynomial by factoring out the greatest common factor, $4 k + 1$ .

$\frac{(4 k + 1) (k - 1)}{4 k^{2} + 11 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3

Factor by grouping.

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Step 3.1

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 $a \cdot c = 4 \cdot 7 = 28$ and whose sum is $b = 11$ .

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Step 3.1.1

Factor $11$ out of $11 k$ .

$\frac{(4 k + 1) (k - 1)}{4 k^{2} + 11 (k) + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3.1.2

Rewrite $11$ as $4$ plus $7$

$\frac{(4 k + 1) (k - 1)}{4 k^{2} + (4 + 7) k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3.1.3

Apply the distributive property.

$\frac{(4 k + 1) (k - 1)}{4 k^{2} + 4 k + 7 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3.2

Factor out the greatest common factor from each group.

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Step 3.2.1

Group the first two terms and the last two terms.

$\frac{(4 k + 1) (k - 1)}{(4 k^{2} + 4 k) + 7 k + 7} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3.2.2

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

$\frac{(4 k + 1) (k - 1)}{4 k (k + 1) + 7 (k + 1)} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 3.3

Factor the polynomial by factoring out the greatest common factor, $k + 1$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{4 k^{2} + 3 k - 7}{16 k^{2} - 1}$

Step 4

Factor by grouping.

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Step 4.1

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 $a \cdot c = 4 \cdot - 7 = - 28$ and whose sum is $b = 3$ .

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Step 4.1.1

Factor $3$ out of $3 k$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{4 k^{2} + 3 (k) - 7}{16 k^{2} - 1}$

Step 4.1.2

Rewrite $3$ as $- 4$ plus $7$

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{4 k^{2} + (- 4 + 7) k - 7}{16 k^{2} - 1}$

Step 4.1.3

Apply the distributive property.

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{4 k^{2} - 4 k + 7 k - 7}{16 k^{2} - 1}$

Step 4.2

Factor out the greatest common factor from each group.

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Step 4.2.1

Group the first two terms and the last two terms.

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(4 k^{2} - 4 k) + 7 k - 7}{16 k^{2} - 1}$

Step 4.2.2

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

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{4 k (k - 1) + 7 (k - 1)}{16 k^{2} - 1}$

Step 4.3

Factor the polynomial by factoring out the greatest common factor, $k - 1$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{16 k^{2} - 1}$

Step 5

Simplify the denominator.

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Step 5.1

Rewrite $16 k^{2}$ as ${(4 k)}^{2}$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{{(4 k)}^{2} - 1}$

Step 5.2

Rewrite $1$ as $1^{2}$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{{(4 k)}^{2} - 1^{2}}$

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 $a = 4 k$ and $b = 1$ .

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{(4 k + 1) (4 k - 1)}$

Step 6

Cancel the common factor of $4 k + 1$ .

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Step 6.1

Cancel the common factor.

$\frac{(4 k + 1) (k - 1)}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{(4 k + 1) (4 k - 1)}$

Step 6.2

Rewrite the expression.

$\frac{k - 1}{(k + 1) (4 k + 7)} \cdot \frac{(k - 1) (4 k + 7)}{4 k - 1}$

Step 7

Cancel the common factor of $4 k + 7$ .

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Step 7.1

Factor $4 k + 7$ out of $(k + 1) (4 k + 7)$ .

$\frac{k - 1}{(4 k + 7) (k + 1)} \cdot \frac{(k - 1) (4 k + 7)}{4 k - 1}$

Step 7.2

Factor $4 k + 7$ out of $(k - 1) (4 k + 7)$ .

$\frac{k - 1}{(4 k + 7) (k + 1)} \cdot \frac{(4 k + 7) (k - 1)}{4 k - 1}$

Step 7.3

Cancel the common factor.

$\frac{k - 1}{(4 k + 7) (k + 1)} \cdot \frac{(4 k + 7) (k - 1)}{4 k - 1}$

Step 7.4

Rewrite the expression.

$\frac{k - 1}{k + 1} \cdot \frac{k - 1}{4 k - 1}$

Step 8

Multiply $\frac{k - 1}{k + 1}$ by $\frac{k - 1}{4 k - 1}$ .

$\frac{(k - 1) (k - 1)}{(k + 1) (4 k - 1)}$

Step 9

Raise $k - 1$ to the power of $1$ .

$\frac{{(k - 1)}^{1} (k - 1)}{(k + 1) (4 k - 1)}$

Step 10

Raise $k - 1$ to the power of $1$ .

$\frac{{(k - 1)}^{1} {(k - 1)}^{1}}{(k + 1) (4 k - 1)}$

Step 11

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

$\frac{{(k - 1)}^{1 + 1}}{(k + 1) (4 k - 1)}$

Step 12

Add $1$ and $1$ .

$\frac{{(k - 1)}^{2}}{(k + 1) (4 k - 1)}$