Find the Equation Using Point-Slope Formula (3,9) , (10,12)

$(3, 9)$ , $(10, 12)$

Step 1

Find the slope of the line between $(3, 9)$ and $(10, 12)$ 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.

$m = \frac{12 - (9)}{10 - (3)}$

Simplify.

Simplify the numerator.

Multiply $- 1$ by $9$ .

$m = \frac{12 - 9}{10 - (3)}$

Subtract $9$ from $12$ .

$m = \frac{3}{10 - (3)}$

Simplify the denominator.

Multiply $- 1$ by $3$ .

$m = \frac{3}{10 - 3}$

Subtract $3$ from $10$ .

$m = \frac{3}{7}$

Step 2

Use the slope $\frac{3}{7}$ and a given point $(3, 9)$ 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 $m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$ .

$y - (9) = \frac{3}{7} \cdot (x - (3))$

Step 3

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

$y - 9 = \frac{3}{7} \cdot (x - 3)$

Step 4

Solve for $y$ .

Simplify $\frac{3}{7} \cdot (x - 3)$ .

Rewrite.

$y - 9 = 0 + 0 + \frac{3}{7} \cdot (x - 3)$

Simplify by adding zeros.

$y - 9 = \frac{3}{7} \cdot (x - 3)$

Apply the distributive property.

$y - 9 = \frac{3}{7} x + \frac{3}{7} \cdot - 3$

Combine $\frac{3}{7}$ and $x$ .

$y - 9 = \frac{3 x}{7} + \frac{3}{7} \cdot - 3$

Multiply $\frac{3}{7} \cdot - 3$ .

Combine $\frac{3}{7}$ and $- 3$ .

$y - 9 = \frac{3 x}{7} + \frac{3 \cdot - 3}{7}$

Multiply $3$ by $- 3$ .

$y - 9 = \frac{3 x}{7} + \frac{- 9}{7}$

Move the negative in front of the fraction.

$y - 9 = \frac{3 x}{7} - \frac{9}{7}$

Move all terms not containing $y$ to the right side of the equation.

Add $9$ to both sides of the equation.

$y = \frac{3 x}{7} - \frac{9}{7} + 9$

To write $9$ as a fraction with a common denominator, multiply by $\frac{7}{7}$ .

$y = \frac{3 x}{7} - \frac{9}{7} + 9 \cdot \frac{7}{7}$

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

$y = \frac{3 x}{7} - \frac{9}{7} + \frac{9 \cdot 7}{7}$

Combine the numerators over the common denominator.

$y = \frac{3 x}{7} + \frac{- 9 + 9 \cdot 7}{7}$

Simplify the numerator.

Multiply $9$ by $7$ .

$y = \frac{3 x}{7} + \frac{- 9 + 63}{7}$

Add $- 9$ and $63$ .

$y = \frac{3 x}{7} + \frac{54}{7}$

Step 5

Reorder terms.

$y = \frac{3}{7} x + \frac{54}{7}$

Step 6

List the equation in different forms.

Slope-intercept form:

$y = \frac{3}{7} x + \frac{54}{7}$

Point-slope form:

$y - 9 = \frac{3}{7} \cdot (x - 3)$

Step 7

Find the Equation Using Point-Slope Formula (3,9) , (10,12)

Related Questions

Support LCMGCF.com by disabling your adblocker.