Coefficient matrix
= Coefficient matrix
{title2=$A=(a_{ij})$}
For a <linear system> $\sum_j a_{ij}x_j=b_i$, the coefficient matrix $A$ contains the coefficients of the unknowns, with one row per equation and one column per unknown. The system becomes $A\mathbf x=\mathbf b$. The <augmented matrix> $[A\mid\mathbf b]$ additionally includes the right-hand-side column; that column is not part of $A$.