There are basically three types of
line equations:
1. y=mx+b
x and y represent a point on the line (x,y)
m represents the slope of the line
b represents the y-intercept
to find the y-intercept let x=0
to find the x-intercept let y=0
2. ax+by=c
x and y represent a point on the line (x,y)
-a/b represents the slope of the line
a, b, and c are constants
the y-intercept is c/b when x=0
the x-intercept is c/a when y=0
3. (y-y1)=m(x-x1)
x1 and y1 represent a point(x1,y1) on the line
m represents the slope of the line
*usually the preferred formula for lines because if you know a point on the line and the slope you know the equation
Parallel lines have the same slope
Perpedicular lines have slopes that are negative reciprocals
e.g. if m is the slope of one line then the slope of the other line is -1/m
Slope can be calculated by using this formula:
(y2-y1)/(x2-x1)
*or is more easily known as rise/run