,

Use to calculate the equation of the line, where represents the slope and represents the y-intercept.

To calculate the equation of the line, use the format.

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

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

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

Reduce the expression by cancelling the common factors.

Cancel the common factor of and .

Rewrite as .

Factor out of .

Reorder terms.

Factor out of .

Cancel the common factors.

Factor out of .

Factor out of .

Factor out of .

Cancel the common factor.

Rewrite the expression.

Add and .

Simplify the denominator.

Multiply by .

Add and .

Multiply by .

Use the formula for the equation of a line to find .

Substitute the value of into the equation.

Substitute the value of into the equation.

Substitute the value of into the equation.

Find the value of .

Rewrite the equation as .

Simplify each term.

Cancel the common factor of .

Factor out of .

Cancel the common factor.

Rewrite the expression.

Multiply by .

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

Add to both sides of the equation.

Add and .

Now that the values of (slope) and (y-intercept) are known, substitute them into to find the equation of the line.

Find the Equation Using Two Points (-4,2) , (4,8)