Answer
-1 0 1
A= 2 1 0
1 -1 1
Work Step by Step
First at all note that A must be a 3x3 matrix in a order. We know that in usual way is as [aij]. So:
1·a11+ 3·a21+ 2·a31= 7
1·a12+ 3·a22+ 2·a32= 1
1·a13+ 3·a23+ 2·a33= 3
2·a11+ 1·a21+ 1·a31= 1
2·a12+ 1·a22+ 1·a32= 0
2·a13+ 1·a23+ 1·a33= 3
4·a11+ 0·a21+ 3·a31=−1
4·a12+ 0·a22+ 3·a32=−3
4·a13+ 0·a23+ 3·a33= 7
By solving this equation we can find that a11=-1, a21-2, also a31=1. And by similar reasoning we can know that a12=0, a22=1, a32=-1 and a13=1, a23=0 , also a33=1 then we can find the A matrix.
