Page "Linear equation" Paragraph 80

In this form, a < sub > 1 </ sub >, a < sub > 2 </ sub >, …, a < sub > n </ sub > are the coefficients, x < sub > 1 </ sub >, x < sub > 2 </ sub >, …, x < sub > n </ sub > are the variables, and b is the constant.

When dealing with three or fewer variables, it is common to replace x < sub > 1 </ sub > with just x, x < sub > 2 </ sub > with y, and x < sub > 3 </ sub > with z, as appropriate.