Pre-Algebra Examples

x + y = 9

$x + y = 9$

Step 1

Subtract

$x$ from both sides of the equation.

$y = 9 - x$

Step 2

Rewrite in slope-intercept form.

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Step 2.1

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 2.2

Reorder

$9$ and

$- x$ .

$y = - x + 9$

Step 3

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

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Step 3.1

Find the values of

$m$ and

$b$ using the form

$y = m x + b$ .

$m = - 1$

$b = 9$

Step 3.2

The slope of the line is the value of

$m$ , and the y-intercept is the value of

$b$ .

Slope:

$- 1$

y-intercept:

$(0, 9)$

Slope:

$- 1$

y-intercept:

$(0, 9)$

Step 4

Any line can be graphed using two points. Select two

$x$ values, and plug them into the equation to find the corresponding

$y$ values.

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Step 4.1

Reorder

$9$ and

$- x$ .

$y = - x + 9$

Step 4.2

Create a table of the

$x$ and

$y$ values.

$\begin{array}{c} x & y \\ 0 & 9 \\ 1 & 8 \end{array}$

Step 5

Graph the line using the slope and the y-intercept, or the points.

Slope:

$- 1$

y-intercept:

$(0, 9)$

$\begin{array}{c} x & y \\ 0 & 9 \\ 1 & 8 \end{array}$

Step 6

$x + y = 9$

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