# Precalculus Examples

,

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.

Simplify.

Simplify the numerator.

Multiply by .

Subtract from .

Simplify the denominator.

Multiply by .

Add and .

Move the negative in front of the fraction.

Use the slope and one of the given points such as to substitute for and in the point-slope form , which is derived from the slope equation .

After finding the slope between the points, use point-slope form to set up the equation. Point-slope is derived from the equation for slope .

Multiply by .

Simplify the right side.

Subtract from .

Simplify .

Write as a fraction with denominator .

Multiply and .

Move to the left of the expression .

Multiply by .

Add to both sides of the equation.

The final answer is the equation in slope-intercept form.