a={{-2,3,1},{3,4,-1}}

MatrixForm[a]

(({{-2, 3, 1}, {3, 4, -1}}))
b={{4,0,-1},{1,-1,2}}

MatrixForm[b]

a+a//MatrixForm

b-b//MatrixForm

3a//MatrixForm

a.b//MatrixForm

(b^2)//MatrixForm

IdentityMatrix[4]//MatrixForm

DiagonalMatrix[{x,y,z,s}]//MatrixForm

c={{1,2,3},{2,-1,-3},{7,8,-9}}

Inverse[c]//MatrixForm

(({{(11/32), (7/16), -(1/32)}, {-(1/32), -(5/16), (3/32)}, {(23/96), (1/16), -(5/96)}}))

Transpose[c]//MatrixForm

c={{1,2,3},{2,-1,-3},{7,8,-9}}

{{1,2,3},{2,-1,-3},{7,8,-9}}

Det[c]

MatrixForm[c]

c[[2]]

c[[2,3]]

c[[3]]=2*c[[2]]-c[[1]]