# Math Help - Help with Linear Algebra proof

1. ## Help with Linear Algebra proof

I've been brushing up on some linear algebra this summer, and came across this problem in a practice book. I'm totally stuck on how to do this!

Prove that if M is an nxn matrix and can be written as

$M=\left(\begin{array}{cc}A&B\\0&C\end{array}\right )$

where A and C are square matrices, then det(M) = det(A)*det(C).

Anyone have a proof for this? I was almost wondering if I should try and use induction for n>=2 since this is true for a 2x2 matrix. Is there an easier (or more correct) way to prove this?

2. Actually, I think it's a lot more simple than that!

I just converted A and C into upper triangular matrices, which in turn makes M upper triangular, which means det(M) = det(A)*det(C). So simple!