Systems of Linear Equations in Three Variables
... A linear equation in three variables x, y, and z is an equation of the form
Ax + By + Cz = D ,
where A, B, C, and D are real numbers with A, B, and C not all equal to zero. (For example, x + 2y + z = 6)
A solution to a linear equation in three variables is an ordered triple of real numbers in the fo ...