Pre-Algebra Examples

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{14 x^{2} + x - 3}$

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 $a \cdot c = 14 \cdot - 3 = - 42$ and whose sum is $b = 1$ .

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Step 1.1.1

Multiply by $1$ .

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{14 x^{2} + 1 x - 3}$

Step 1.1.2

Rewrite $1$ as $- 6$ plus $7$

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{14 x^{2} + (- 6 + 7) x - 3}$

Step 1.1.3

Apply the distributive property.

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{14 x^{2} - 6 x + 7 x - 3}$

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.

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{(14 x^{2} - 6 x) + 7 x - 3}$

Step 1.2.2

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

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{2 x (7 x - 3) + 1 (7 x - 3)}$

Step 1.3

Factor the polynomial by factoring out the greatest common factor, $7 x - 3$ .

$\frac{5}{7 x - 3} - \frac{2}{2 x + 1} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 2

To write $\frac{5}{7 x - 3}$ as a fraction with a common denominator, multiply by $\frac{2 x + 1}{2 x + 1}$ .

$\frac{5}{7 x - 3} \cdot \frac{2 x + 1}{2 x + 1} - \frac{2}{2 x + 1} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 3

To write $- \frac{2}{2 x + 1}$ as a fraction with a common denominator, multiply by $\frac{7 x - 3}{7 x - 3}$ .

$\frac{5}{7 x - 3} \cdot \frac{2 x + 1}{2 x + 1} - \frac{2}{2 x + 1} \cdot \frac{7 x - 3}{7 x - 3} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 4

Write each expression with a common denominator of $(7 x - 3) (2 x + 1)$ , by multiplying each by an appropriate factor of $1$ .

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Step 4.1

Multiply $\frac{5}{7 x - 3}$ by $\frac{2 x + 1}{2 x + 1}$ .

$\frac{5 (2 x + 1)}{(7 x - 3) (2 x + 1)} - \frac{2}{2 x + 1} \cdot \frac{7 x - 3}{7 x - 3} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 4.2

Multiply $\frac{2}{2 x + 1}$ by $\frac{7 x - 3}{7 x - 3}$ .

$\frac{5 (2 x + 1)}{(7 x - 3) (2 x + 1)} - \frac{2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 4.3

Reorder the factors of $(7 x - 3) (2 x + 1)$ .

$\frac{5 (2 x + 1)}{(2 x + 1) (7 x - 3)} - \frac{2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 5

Combine the numerators over the common denominator.

$\frac{5 (2 x + 1) - 2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6

Simplify the numerator.

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Step 6.1

Apply the distributive property.

$\frac{5 (2 x) + 5 \cdot 1 - 2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.2

Multiply $2$ by $5$ .

$\frac{10 x + 5 \cdot 1 - 2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.3

Multiply $5$ by $1$ .

$\frac{10 x + 5 - 2 (7 x - 3)}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.4

Apply the distributive property.

$\frac{10 x + 5 - 2 (7 x) - 2 \cdot - 3}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.5

Multiply $7$ by $- 2$ .

$\frac{10 x + 5 - 14 x - 2 \cdot - 3}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.6

Multiply $- 2$ by $- 3$ .

$\frac{10 x + 5 - 14 x + 6}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.7

Subtract $14 x$ from $10 x$ .

$\frac{- 4 x + 5 + 6}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 6.8

Add $5$ and $6$ .

$\frac{- 4 x + 11}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(7 x - 3) (2 x + 1)}$

Step 7

Combine into one fraction.

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Step 7.1

Reorder the factors of $(7 x - 3) (2 x + 1)$ .

$\frac{- 4 x + 11}{(2 x + 1) (7 x - 3)} + \frac{4 x}{(2 x + 1) (7 x - 3)}$

Step 7.2

Combine the numerators over the common denominator.

$\frac{- 4 x + 11 + 4 x}{(2 x + 1) (7 x - 3)}$

Step 8

Simplify the numerator.

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Step 8.1

Add $- 4 x$ and $4 x$ .

$\frac{0 + 11}{(2 x + 1) (7 x - 3)}$

Step 8.2

Add $0$ and $11$ .

$\frac{11}{(2 x + 1) (7 x - 3)}$