A linear equation is an algebraic equation of the form
 |
where the coefficients 
, ..., 
and 
are constants, and the 
are not all zero. It involves no
products of distinct variables
or powers of variables greater than one.
For a nonvertical line in the plane, a linear equation in two variables can be written in slope-intercept form,
 |
where 
is the slope and 
is the y-intercept.
Linear equations can also be written in standard form,
intercept form, and other forms.
Equations such as 
and 
are linear equations of a single variable, and 
is an example of a linear
equation with three variables.
