even function
f(-x) = f(x)
not always a function
-f(x) = f(x)
odd function
f(-x) = -f(x)
even symmetry
y axis
not always a function symmetry
x axis
odd symmetry
origin
m
y2-y1 / x2-x1
point slope form
y - y1 = m(x - x1)
slope intercept form
y = mx + b
general form
Ax + By + C = 0
standard form
Ax + By = C
parallel lines
same slope
perpendicular lines
negative reciprocal slope
distance between a line and a point
absolute value of (Ax + By + C) / square root of (A^2 + B^2)