If a 4×4 matrix A with rows v1, v2, v3, and v4 has determinant detA=7,
row 1 [ v1]
row 2 [ 4v2 + 9v4 ]
row 3 [ v3 ]
row 4 [3v2 + 2v4 ]
what is the det of this matrix?
as you said, it is 7.
Not sure how your determinant looks. Each row needs four elements ...
Expand by minors to evaluate it.