Find the Equation Using Point-Slope Formula (-9,0) , (0,7)

$(- 9, 0)$ , $(0, 7)$

Step 1

Find the slope of the line between $(- 9, 0)$ and $(0, 7)$ using $m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$ , which is the change of $y$ over the change of $x$ .

Slope is equal to the change in $y$ over the change in $x$ , or rise over run.

$m = \frac{change in y}{change in x}$

The change in $x$ is equal to the difference in x-coordinates (also called run), and the change in $y$ is equal to the difference in y-coordinates (also called rise).

$m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$

Substitute in the values of $x$ and $y$ into the equation to find the slope.

$m = \frac{7 - (0)}{0 - (- 9)}$

Simplify.

Simplify the numerator.

Multiply $- 1$ by $0$ .

$m = \frac{7 + 0}{0 - (- 9)}$

Add $7$ and $0$ .

$m = \frac{7}{0 - (- 9)}$

Simplify the denominator.

Multiply $- 1$ by $- 9$ .

$m = \frac{7}{0 + 9}$

Add $0$ and $9$ .

$m = \frac{7}{9}$

Step 2

Use the slope $\frac{7}{9}$ and a given point $(- 9, 0)$ to substitute for $x_{1}$ and $y_{1}$ in the point-slope form $y - y_{1} = m (x - x_{1})$ , which is derived from the slope equation $m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$ .

$y - (0) = \frac{7}{9} \cdot (x - (- 9))$

Step 3

Simplify the equation and keep it in point-slope form.

$y + 0 = \frac{7}{9} \cdot (x + 9)$

Step 4

Solve for $y$ .

Add $y$ and $0$ .

$y = \frac{7}{9} \cdot (x + 9)$

Simplify $\frac{7}{9} \cdot (x + 9)$ .

Apply the distributive property.

$y = \frac{7}{9} x + \frac{7}{9} \cdot 9$

Combine $\frac{7}{9}$ and $x$ .

$y = \frac{7 x}{9} + \frac{7}{9} \cdot 9$

Cancel the common factor of $9$ .

Cancel the common factor.

$y = \frac{7 x}{9} + \frac{7}{9} \cdot 9$

Rewrite the expression.

$y = \frac{7 x}{9} + 7$

Step 5

Reorder terms.

$y = \frac{7}{9} x + 7$

Step 6

List the equation in different forms.

Slope-intercept form:

$y = \frac{7}{9} x + 7$

Point-slope form:

$y + 0 = \frac{7}{9} \cdot (x + 9)$

Step 7

Find the Equation Using Point-Slope Formula (-9,0) , (0,7)

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