A=matrix([[1,0],[2,1]])
B=matrix([[1,2],[0,1]])
amb=dot(A,B)
print(amb)
bma=dot(B,A)
print(bma)
ainv=inv(A)
print(ainv)
binv=inv(B)
print(binv)
ambinv=inv(amb)
print(ambinv)