Pre-Algebra Examples

$3 x - y = 9$

Step 1

Rewrite in slope-intercept form.

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Step 1.1

The slope-intercept form is $y = m x + b$ , where $m$ is the slope and $b$ is the y-intercept.

$y = m x + b$

Step 1.2

Subtract $3 x$ from both sides of the equation.

$- y = 9 - 3 x$

Step 1.3

Divide each term in $- y = 9 - 3 x$ by $- 1$ and simplify.

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Step 1.3.1

Divide each term in $- y = 9 - 3 x$ by $- 1$ .

$\frac{- y}{- 1} = \frac{9}{- 1} + \frac{- 3 x}{- 1}$

Step 1.3.2

Simplify the left side.

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Step 1.3.2.1

Dividing two negative values results in a positive value.

$\frac{y}{1} = \frac{9}{- 1} + \frac{- 3 x}{- 1}$

Step 1.3.2.2

Divide $y$ by $1$ .

$y = \frac{9}{- 1} + \frac{- 3 x}{- 1}$

Step 1.3.3

Simplify the right side.

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Step 1.3.3.1

Simplify each term.

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Step 1.3.3.1.1

Divide $9$ by $- 1$ .

$y = - 9 + \frac{- 3 x}{- 1}$

Step 1.3.3.1.2

Move the negative one from the denominator of $\frac{- 3 x}{- 1}$ .

$y = - 9 - 1 \cdot (- 3 x)$

Step 1.3.3.1.3

Rewrite $- 1 \cdot (- 3 x)$ as $- (- 3 x)$ .

$y = - 9 - (- 3 x)$

Step 1.3.3.1.4

Multiply $- 3$ by $- 1$ .

$y = - 9 + 3 x$

Step 1.4

Reorder $- 9$ and $3 x$ .

$y = 3 x - 9$

Step 2

Use the slope-intercept form to find the slope and y-intercept.

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Step 2.1

Find the values of $m$ and $b$ using the form $y = m x + b$ .

$m = 3$

$b = - 9$

Step 2.2

The slope of the line is the value of $m$ , and the y-intercept is the value of $b$ .

Slope: $3$

y-intercept: $(0, - 9)$

Slope: $3$

y-intercept: $(0, - 9)$

Step 3