## Precalculus (6th Edition) Blitzer

A linear equation of the multiplication matrix containing three unknown variables $x,y,z$ is: \begin{align} & {{a}_{11}}x+{{a}_{12}}y+{{a}_{13}}z={{b}_{1}} \\ & {{a}_{21}}x+{{a}_{22}}y+{{a}_{23}}z={{b}_{2}} \\ & {{a}_{31}}x+{{a}_{32}}y+{{a}_{33}}z={{b}_{3}} \end{align}