[tex]\begin{gathered} A=\begin{bmatrix}{a} & {2} & {3} \\ 4{} & {b} & {6} \\ {c} & {8} & {-7}\end{bmatrix} \\ B=\begin{bmatrix}{5} & {1} & {-2} \\ {-1} & {3} & {4} \\ {2} & {d} & {e}\end{bmatrix} \\ AB_{11}=5a+4=14 \\ AB_{12}=a+6+3d=-1 \\ AB_{13}=-2a+8+3e=f \\ AB_{21}=32-b=20 \\ AB_{22}=4+3b+6d=22 \\ AB_{23}=-8+4b+6e=70 \\ AB_{31}=5c-22=-27 \\ AB_{32}=c+24-7d=44 \\ AB_{33}=-2c+32-7e=-1 \\ a=\frac{14-4}{5}=2 \\ d=\frac{-1-6-2}{3}=-3 \\ b=32-20=12 \\ e=\frac{70+8-4\cdot12}{6}=5 \\ f=-2\cdot2+8+3\cdot5=19 \\ c=\frac{-27+22}{5}=-1 \end{gathered}[/tex]
