Originally Posted by

**BlackBlaze** Hi, I'm not sure how much help you guys can give, since this isn't really a textbook question...More of a "how should I study this".

I find I'm able to do calculations and the like with ease in my linear algebra course, but it's the proofs that really get me. Every time I see a question that says "Show that..." or "Prove that..." I'm not able to figure out a method to complete the question. If I see the answer, I can understand just fine, but I don't understand how any person can think of that method to solve it.

For example, one of the midterm questions I received:

"If A and B are n by n matrices, and given that AB is invertible, prove that B must be invertible."

I draw a blank when I try to solve this question on my own.

When the solutions came up, I understood perfectly. To prove B is invertible, Bx = 0 must only have the trivial solution of x = 0. And then you start off with (AB)x = 0 and can easily go from there.

If you go onto take a "proof" course, this will become much clearer. Trying to learn how to prove things while taking linear algebra isn't easy

So, are there some tips or strategies to get better at doing these questions?