lines with opposite reciprocal slopes of each other
lines with the same slope
lines that are straight up and down, undefined slope, x=...
lines that are straight side to side, slope of 0, y=...
a graph of non-linear data points
best fit line
the line that most clearly approximates the data in a scatter plot
slope intercept form
Point slope form
y-y1 = m(x-x1), where m is the slope and (x1,y1) is the point the line is passing through.
Ax + By=C, where A, B, and C are not decimals or fractions, where A and B are not both zero, and where A is not a negative.