notice that the matrix (or determinant of a matrix, not sure which you are doing) on the left is the same as on the right, except for the k. so we must have k=1, otherwise the equality wouldn't hold
I am trying to do a matrices. I think my answer would be 1, but I am confused about the question too.
well, one way to look at it is that the k is a scalar multiple, so you can multiply each element within the matrix by k, then to have equality, you would equate corresponding components.