一、形式

\(\begin{cases} A_{11}X_{1} + A_{12}X_{2} + ......+A_{1n}X_{n}=B_{1} \ A_{21}X_{1} + A_{22}X_{2} + ......+A_{2n}X_{n}=B_{2}\ ...... A_{n1}X_{1} + A_{n2}X_{2} + ......+A_{nn}X_{n}=B_{n} \end{cases}\)\(\begin{cases} A_{11}X_{1} + A_{12}X_{2}