Compute AB and BA, which ever exists when A = [(2,1)(3,2)(-1,1)] B = [(1,0,1)(-1,2,1)]

Hi, I have a question and I hope anyone could answer it:

Compute AB and BA, which ever exists when

A = (begin{bmatrix}
2 & 1 \[0.3em] 3 & 2 \[0.3em] -1 & 1
end{bmatrix})and B = (begin{bmatrix}
1&0 & 1 \[0.3em] -1& 2 & 1\[0.3em] -1 & 2& 1
end{bmatrix})

A = [(2,1)(3,2)(-1,1)]

B = [(1,0,1)(-1,2,1)]