Pre-Algebra Examples

$\frac{3 x - 1}{x - 4} - \frac{6 x + 5}{3 x + 9} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1

Simplify $\frac{3 x - 1}{x - 4} - \frac{6 x + 5}{3 x + 9}$ .

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Step 1.1

Factor $3$ out of $3 x + 9$ .

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Step 1.1.1

Factor $3$ out of $3 x$ .

$\frac{3 x - 1}{x - 4} - \frac{6 x + 5}{3 (x) + 9} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.1.2

Factor $3$ out of $9$ .

$\frac{3 x - 1}{x - 4} - \frac{6 x + 5}{3 x + 3 \cdot 3} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.1.3

Factor $3$ out of $3 x + 3 \cdot 3$ .

$\frac{3 x - 1}{x - 4} - \frac{6 x + 5}{3 (x + 3)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.2

To write $\frac{3 x - 1}{x - 4}$ as a fraction with a common denominator, multiply by $\frac{3 (x + 3)}{3 (x + 3)}$ .

$\frac{3 x - 1}{x - 4} \cdot \frac{3 (x + 3)}{3 (x + 3)} - \frac{6 x + 5}{3 (x + 3)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.3

To write $- \frac{6 x + 5}{3 (x + 3)}$ as a fraction with a common denominator, multiply by $\frac{x - 4}{x - 4}$ .

$\frac{3 x - 1}{x - 4} \cdot \frac{3 (x + 3)}{3 (x + 3)} - \frac{6 x + 5}{3 (x + 3)} \cdot \frac{x - 4}{x - 4} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.4

Write each expression with a common denominator of $(x - 4) \cdot 3 (x + 3)$ , by multiplying each by an appropriate factor of $1$ .

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Step 1.4.1

Multiply $\frac{3 x - 1}{x - 4}$ by $\frac{3 (x + 3)}{3 (x + 3)}$ .

$\frac{(3 x - 1) (3 (x + 3))}{(x - 4) (3 (x + 3))} - \frac{6 x + 5}{3 (x + 3)} \cdot \frac{x - 4}{x - 4} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.4.2

Multiply $\frac{6 x + 5}{3 (x + 3)}$ by $\frac{x - 4}{x - 4}$ .

$\frac{(3 x - 1) (3 (x + 3))}{(x - 4) (3 (x + 3))} - \frac{(6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.4.3

Reorder the factors of $(x - 4) (3 (x + 3))$ .

$\frac{(3 x - 1) (3 (x + 3))}{3 (x + 3) (x - 4)} - \frac{(6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.5

Combine the numerators over the common denominator.

$\frac{(3 x - 1) (3 (x + 3)) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6

Simplify the numerator.

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Step 1.6.1

Apply the distributive property.

$\frac{(3 x \cdot 3 - 1 \cdot 3) (x + 3) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.2

Multiply $3$ by $3$ .

$\frac{(9 x - 1 \cdot 3) (x + 3) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.3

Multiply $- 1$ by $3$ .

$\frac{(9 x - 3) (x + 3) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.4

Expand $(9 x - 3) (x + 3)$ using the FOIL Method.

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Step 1.6.4.1

Apply the distributive property.

$\frac{9 x (x + 3) - 3 (x + 3) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.4.2

Apply the distributive property.

$\frac{9 x \cdot x + 9 x \cdot 3 - 3 (x + 3) - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.4.3

Apply the distributive property.

$\frac{9 x \cdot x + 9 x \cdot 3 - 3 x - 3 \cdot 3 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.5

Simplify and combine like terms.

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Step 1.6.5.1

Simplify each term.

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Step 1.6.5.1.1

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

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Step 1.6.5.1.1.1

Move $x$ .

$\frac{9 (x \cdot x) + 9 x \cdot 3 - 3 x - 3 \cdot 3 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.5.1.1.2

Multiply $x$ by $x$ .

$\frac{9 x^{2} + 9 x \cdot 3 - 3 x - 3 \cdot 3 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.5.1.2

Multiply $3$ by $9$ .

$\frac{9 x^{2} + 27 x - 3 x - 3 \cdot 3 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.5.1.3

Multiply $- 3$ by $3$ .

$\frac{9 x^{2} + 27 x - 3 x - 9 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.5.2

Subtract $3 x$ from $27 x$ .

$\frac{9 x^{2} + 24 x - 9 - (6 x + 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.6

Apply the distributive property.

$\frac{9 x^{2} + 24 x - 9 + (- (6 x) - 1 \cdot 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.7

Multiply $6$ by $- 1$ .

$\frac{9 x^{2} + 24 x - 9 + (- 6 x - 1 \cdot 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.8

Multiply $- 1$ by $5$ .

$\frac{9 x^{2} + 24 x - 9 + (- 6 x - 5) (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.9

Expand $(- 6 x - 5) (x - 4)$ using the FOIL Method.

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Step 1.6.9.1

Apply the distributive property.

$\frac{9 x^{2} + 24 x - 9 - 6 x (x - 4) - 5 (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.9.2

Apply the distributive property.

$\frac{9 x^{2} + 24 x - 9 - 6 x \cdot x - 6 x \cdot - 4 - 5 (x - 4)}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.9.3

Apply the distributive property.

$\frac{9 x^{2} + 24 x - 9 - 6 x \cdot x - 6 x \cdot - 4 - 5 x - 5 \cdot - 4}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.10

Simplify and combine like terms.

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Step 1.6.10.1

Simplify each term.

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Step 1.6.10.1.1

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

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Step 1.6.10.1.1.1

Move $x$ .

$\frac{9 x^{2} + 24 x - 9 - 6 (x \cdot x) - 6 x \cdot - 4 - 5 x - 5 \cdot - 4}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.10.1.1.2

Multiply $x$ by $x$ .

$\frac{9 x^{2} + 24 x - 9 - 6 x^{2} - 6 x \cdot - 4 - 5 x - 5 \cdot - 4}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.10.1.2

Multiply $- 4$ by $- 6$ .

$\frac{9 x^{2} + 24 x - 9 - 6 x^{2} + 24 x - 5 x - 5 \cdot - 4}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.10.1.3

Multiply $- 5$ by $- 4$ .

$\frac{9 x^{2} + 24 x - 9 - 6 x^{2} + 24 x - 5 x + 20}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.10.2

Subtract $5 x$ from $24 x$ .

$\frac{9 x^{2} + 24 x - 9 - 6 x^{2} + 19 x + 20}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.11

Subtract $6 x^{2}$ from $9 x^{2}$ .

$\frac{3 x^{2} + 24 x - 9 + 19 x + 20}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.12

Add $24 x$ and $19 x$ .

$\frac{3 x^{2} + 43 x - 9 + 20}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 1.6.13

Add $- 9$ and $20$ .

$\frac{3 x^{2} + 43 x + 11}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 15} - \frac{11}{45}$

Step 2

Factor $5$ out of $5 x + 15$ .

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Step 2.1

Factor $5$ out of $5 x$ .

$\frac{3 x^{2} + 43 x + 11}{3 (x + 3) (x - 4)} = \frac{9}{5 (x) + 15} - \frac{11}{45}$

Step 2.2

Factor $5$ out of $15$ .

$\frac{3 x^{2} + 43 x + 11}{3 (x + 3) (x - 4)} = \frac{9}{5 x + 5 \cdot 3} - \frac{11}{45}$

Step 2.3

Factor $5$ out of $5 x + 5 \cdot 3$ .

$\frac{3 x^{2} + 43 x + 11}{3 (x + 3) (x - 4)} = \frac{9}{5 (x + 3)} - \frac{11}{45}$

Step 3

Graph each side of the equation. The solution is the x-value of the point of intersection.

$x \approx - 9.18060102, - 0.69439898$

Step 4