Linear Equations Key Formulas

Front

How to determine the slope given two points in ordered pair form? point (x1,y1) and (a,b)

Back

slope m = (b-y1) / (a-x1).

Front

Slope of a horizontal line

Back

m=0 , slope is zero

Front

slope of a vertical line

Back

m=undefined

Front

equation of a horizontal line through the point (a,b)

Back

y=a

Front

equation of a vertical line through point (a,b)

Back

x = a

Front

Equation of a line in slope-intercept form

Back

f(x) = mx + b

or

y = mx +b

(remember f(x) is function notation which means y )

Front

point-slope form for equation of a line

Back

y - y1 = m (x - x1)

where y is the output, dependent variable,

x is the independent input variable and the point is (x1,y1) which will be given numbers. the slope numerical value is m.

Front

General form for equation of a line

Back

ax + by + c = 0

where your variables are x and y, and a,b,c are any real number (but a and b cannot both be 0)

Front

x - 7 = 0 is what type of line

Back

This is really x = 7 , a vertical line with an undefined slope

Front

Define x-intercept

Back

A point on the x-axis

ordered pair form is (a,0)

the value of x when you let y = 0