MATH 121
FORMULAS FOR LINEAR FUNCTIONS

Lines through P1 and P2 parallel to x- and y-axes intersect at P3(x2, y1) .

y-distance: y2 – y1
x-distance: x2 – x1

Distance Formula: 

    

Midpoints:

    

    

slope =

 

 

Line parallel to x-axis, y2 – y1 = 0 and

Line parallel to y-axis, x2 – x1 = 0 and , so the slope is undefined.

Linear Function:

Standard form: Ax + By + C = 0 (B ¹ 0)

y -form:

Slope-intercept form: y = m x + b ;   m = slope, b = y -intercept

Point- slope form: y – y1 = m(x – x1)

2- point form: