Finite Math Examples

$\frac{6 x}{7 x^{2} - 6 x - 16} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1

Simplify each term.

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Step 1.1

Factor by grouping.

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Step 1.1.1

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 $a \cdot c = 7 \cdot - 16 = - 112$ and whose sum is $b = - 6$ .

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Step 1.1.1.1

Factor $- 6$ out of $- 6 x$ .

$\frac{6 x}{7 x^{2} - 6 (x) - 16} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.1.1.2

Rewrite $- 6$ as $8$ plus $- 14$

$\frac{6 x}{7 x^{2} + (8 - 14) x - 16} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.1.1.3

Apply the distributive property.

$\frac{6 x}{7 x^{2} + 8 x - 14 x - 16} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.1.2

Factor out the greatest common factor from each group.

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Step 1.1.2.1

Group the first two terms and the last two terms.

$\frac{6 x}{(7 x^{2} + 8 x) - 14 x - 16} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.1.2.2

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

$\frac{6 x}{x (7 x + 8) - 2 (7 x + 8)} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.1.3

Factor the polynomial by factoring out the greatest common factor, $7 x + 8$ .

$\frac{6 x}{(7 x + 8) (x - 2)} - \frac{5 x}{7 x^{2} - 15 + 2}$

Step 1.2

Add $- 15$ and $2$ .

$\frac{6 x}{(7 x + 8) (x - 2)} - \frac{5 x}{7 x^{2} - 13}$

Step 2

To write $\frac{6 x}{(7 x + 8) (x - 2)}$ as a fraction with a common denominator, multiply by $\frac{7 x^{2} - 13}{7 x^{2} - 13}$ .

$\frac{6 x}{(7 x + 8) (x - 2)} \cdot \frac{7 x^{2} - 13}{7 x^{2} - 13} - \frac{5 x}{7 x^{2} - 13}$

Step 3

To write $- \frac{5 x}{7 x^{2} - 13}$ as a fraction with a common denominator, multiply by $\frac{(7 x + 8) (x - 2)}{(7 x + 8) (x - 2)}$ .

$\frac{6 x}{(7 x + 8) (x - 2)} \cdot \frac{7 x^{2} - 13}{7 x^{2} - 13} - \frac{5 x}{7 x^{2} - 13} \cdot \frac{(7 x + 8) (x - 2)}{(7 x + 8) (x - 2)}$

Step 4

Write each expression with a common denominator of $(7 x + 8) (x - 2) (7 x^{2} - 13)$ , by multiplying each by an appropriate factor of $1$ .

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Step 4.1

Multiply $\frac{6 x}{(7 x + 8) (x - 2)}$ by $\frac{7 x^{2} - 13}{7 x^{2} - 13}$ .

$\frac{6 x (7 x^{2} - 13)}{(7 x + 8) (x - 2) (7 x^{2} - 13)} - \frac{5 x}{7 x^{2} - 13} \cdot \frac{(7 x + 8) (x - 2)}{(7 x + 8) (x - 2)}$

Step 4.2

Multiply $\frac{5 x}{7 x^{2} - 13}$ by $\frac{(7 x + 8) (x - 2)}{(7 x + 8) (x - 2)}$ .

$\frac{6 x (7 x^{2} - 13)}{(7 x + 8) (x - 2) (7 x^{2} - 13)} - \frac{5 x ((7 x + 8) (x - 2))}{(7 x^{2} - 13) ((7 x + 8) (x - 2))}$

Step 4.3

Reorder the factors of $(7 x + 8) (x - 2) (7 x^{2} - 13)$ .

$\frac{6 x (7 x^{2} - 13)}{(7 x + 8) (7 x^{2} - 13) (x - 2)} - \frac{5 x ((7 x + 8) (x - 2))}{(7 x^{2} - 13) ((7 x + 8) (x - 2))}$

Step 4.4

Reorder the factors of $(7 x^{2} - 13) ((7 x + 8) (x - 2))$ .

$\frac{6 x (7 x^{2} - 13)}{(7 x + 8) (7 x^{2} - 13) (x - 2)} - \frac{5 x ((7 x + 8) (x - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 5

Combine the numerators over the common denominator.

$\frac{6 x (7 x^{2} - 13) - 5 x ((7 x + 8) (x - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6

Simplify the numerator.

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Step 6.1

Factor $x$ out of $6 x (7 x^{2} - 13) - 5 x ((7 x + 8) (x - 2))$ .

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Step 6.1.1

Factor $x$ out of $6 x (7 x^{2} - 13)$ .

$\frac{x (6 (7 x^{2} - 13)) - 5 x ((7 x + 8) (x - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.1.2

Factor $x$ out of $- 5 x ((7 x + 8) (x - 2))$ .

$\frac{x (6 (7 x^{2} - 13)) + x (- 5 ((7 x + 8) (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.1.3

Factor $x$ out of $x (6 (7 x^{2} - 13)) + x (- 5 ((7 x + 8) (x - 2)))$ .

$\frac{x (6 (7 x^{2} - 13) - 5 ((7 x + 8) (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.2

Apply the distributive property.

$\frac{x (6 (7 x^{2}) + 6 \cdot - 13 - 5 ((7 x + 8) (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.3

Multiply $7$ by $6$ .

$\frac{x (42 x^{2} + 6 \cdot - 13 - 5 ((7 x + 8) (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.4

Multiply $6$ by $- 13$ .

$\frac{x (42 x^{2} - 78 - 5 ((7 x + 8) (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.5

Expand $(7 x + 8) (x - 2)$ using the FOIL Method.

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Step 6.5.1

Apply the distributive property.

$\frac{x (42 x^{2} - 78 - 5 (7 x (x - 2) + 8 (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.5.2

Apply the distributive property.

$\frac{x (42 x^{2} - 78 - 5 (7 x \cdot x + 7 x \cdot - 2 + 8 (x - 2)))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.5.3

Apply the distributive property.

$\frac{x (42 x^{2} - 78 - 5 (7 x \cdot x + 7 x \cdot - 2 + 8 x + 8 \cdot - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.6

Simplify and combine like terms.

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Step 6.6.1

Simplify each term.

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Step 6.6.1.1

Multiply $x$ by $x$ by adding the exponents.

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Step 6.6.1.1.1

Move $x$ .

$\frac{x (42 x^{2} - 78 - 5 (7 (x \cdot x) + 7 x \cdot - 2 + 8 x + 8 \cdot - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.6.1.1.2

Multiply $x$ by $x$ .

$\frac{x (42 x^{2} - 78 - 5 (7 x^{2} + 7 x \cdot - 2 + 8 x + 8 \cdot - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.6.1.2

Multiply $- 2$ by $7$ .

$\frac{x (42 x^{2} - 78 - 5 (7 x^{2} - 14 x + 8 x + 8 \cdot - 2))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.6.1.3

Multiply $8$ by $- 2$ .

$\frac{x (42 x^{2} - 78 - 5 (7 x^{2} - 14 x + 8 x - 16))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.6.2

Add $- 14 x$ and $8 x$ .

$\frac{x (42 x^{2} - 78 - 5 (7 x^{2} - 6 x - 16))}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.7

Apply the distributive property.

$\frac{x (42 x^{2} - 78 - 5 (7 x^{2}) - 5 (- 6 x) - 5 \cdot - 16)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.8

Simplify.

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Step 6.8.1

Multiply $7$ by $- 5$ .

$\frac{x (42 x^{2} - 78 - 35 x^{2} - 5 (- 6 x) - 5 \cdot - 16)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.8.2

Multiply $- 6$ by $- 5$ .

$\frac{x (42 x^{2} - 78 - 35 x^{2} + 30 x - 5 \cdot - 16)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.8.3

Multiply $- 5$ by $- 16$ .

$\frac{x (42 x^{2} - 78 - 35 x^{2} + 30 x + 80)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.9

Subtract $35 x^{2}$ from $42 x^{2}$ .

$\frac{x (7 x^{2} - 78 + 30 x + 80)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$

Step 6.10

Add $- 78$ and $80$ .

$\frac{x (7 x^{2} + 30 x + 2)}{(7 x + 8) (7 x^{2} - 13) (x - 2)}$