You can do that, also
A:=<<1|2|3>,<4|5|6>,<7|8|9>>;
easier to visualise sometimes,
The row operation stuff didnt work for me when i did this
M:=(A[2..3,1..2]);
Anyway, don't forgot to import the modules
with(plot);
with(LinearAlgebra);
inverse is arc<<insert sin/cos/tan/sec/csc/cot...