,

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.

Multiply by .

Subtract from .

The expression contains a division by The expression is undefined.

Undefined

Since the slope is , this is a vertical line. Since a vertical line has a constant value of and the line must pass through , the equation is .

Find the Equation Using Two Points (5,5) , (5,4)