Algebra Examples

$\frac{x}{3} = \frac{7 x}{12 x - 15}$

Step 1

Factor $3$ out of $12 x - 15$ .

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Step 1.1

Factor $3$ out of $12 x$ .

$\frac{x}{3} = \frac{7 x}{3 (4 x) - 15}$

Step 1.2

Factor $3$ out of $- 15$ .

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

Step 1.3

Factor $3$ out of $3 (4 x) + 3 (- 5)$ .

$\frac{x}{3} = \frac{7 x}{3 (4 x - 5)}$

Step 2

Multiply the numerator of the first fraction by the denominator of the second fraction. Set this equal to the product of the denominator of the first fraction and the numerator of the second fraction.

$x (3 (4 x - 5)) = 3 (7 x)$

Step 3

Solve the equation for $x$ .

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Step 3.1

Simplify $x (3 (4 x - 5))$ .

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Step 3.1.1

Rewrite.

$0 + 0 + x (3 (4 x - 5)) = 3 \cdot (7 x)$

Step 3.1.2

Simplify by multiplying through.

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Step 3.1.2.1

Add $0$ and $0$ .

$0 + x (3 (4 x - 5)) = 3 \cdot (7 x)$

Step 3.1.2.2

Rewrite using the commutative property of multiplication.

$3 x (4 x - 5) = 3 \cdot (7 x)$

Step 3.1.2.3

Apply the distributive property.

$3 x (4 x) + 3 x \cdot - 5 = 3 \cdot (7 x)$

Step 3.1.2.4

Simplify the expression.

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Step 3.1.2.4.1

Rewrite using the commutative property of multiplication.

$3 \cdot 4 x \cdot x + 3 x \cdot - 5 = 3 \cdot (7 x)$

Step 3.1.2.4.2

Multiply $- 5$ by $3$ .

$3 \cdot 4 x \cdot x - 15 x = 3 \cdot (7 x)$

Step 3.1.3

Simplify each term.

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Step 3.1.3.1

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

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Step 3.1.3.1.1

Move $x$ .

$3 \cdot 4 (x \cdot x) - 15 x = 3 \cdot (7 x)$

Step 3.1.3.1.2

Multiply $x$ by $x$ .

$3 \cdot 4 x^{2} - 15 x = 3 \cdot (7 x)$

Step 3.1.3.2

Multiply $3$ by $4$ .

$12 x^{2} - 15 x = 3 \cdot (7 x)$

Step 3.2

Multiply $7$ by $3$ .

$12 x^{2} - 15 x = 21 x$

Step 3.3

Move all terms containing $x$ to the left side of the equation.

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Step 3.3.1

Subtract $21 x$ from both sides of the equation.

$12 x^{2} - 15 x - 21 x = 0$

Step 3.3.2

Subtract $21 x$ from $- 15 x$ .

$12 x^{2} - 36 x = 0$

Step 3.4

Factor $12 x$ out of $12 x^{2} - 36 x$ .

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Step 3.4.1

Factor $12 x$ out of $12 x^{2}$ .

$12 x (x) - 36 x = 0$

Step 3.4.2

Factor $12 x$ out of $- 36 x$ .

$12 x (x) + 12 x (- 3) = 0$

Step 3.4.3

Factor $12 x$ out of $12 x (x) + 12 x (- 3)$ .

$12 x (x - 3) = 0$

Step 3.5

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x = 0$

$x - 3 = 0$

Step 3.6

Set $x$ equal to $0$ .

$x = 0$

Step 3.7

Set $x - 3$ equal to $0$ and solve for $x$ .

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Step 3.7.1

Set $x - 3$ equal to $0$ .

$x - 3 = 0$

Step 3.7.2

Add $3$ to both sides of the equation.

$x = 3$

Step 3.8

The final solution is all the values that make $12 x (x - 3) = 0$ true.

$x = 0, 3$