Math Help - Matrix doing a cofactor expansion

Evaluate the determinant of the following matrix A =


by doing a co-factor expansion.

Please expalin how to do it, thank you!
this is the exercise on my task

If you have:



The cofactor for is the determinant of:



The cofactor for is negative(-) of the determinant of:



The cofactor for is the determinant of:

Why are you being asked to do a "co-factor expansion" if you don't know what that is?

I would recommend starting your co-factor expansion using the first column. That way you just have 2 times and expand that determinant on the second column. Do you see why?

Originally Posted by HallsofIvy

Why are you being asked to do a "co-factor expansion" if you don't know what that is?

I would recommend starting your co-factor expansion using the first column. That way you just have 2 times and expand that determinant on the second column. Do you see why?

I am sorry, I am not good on maths , can you explain more please !!!
I don't understand what is "just have 2 times" mean?
Is it mean 2 times every number 1 & 0 & 3 & 1 \\ 2 & 0 & 0 & 1 \\ 0 & 1 & 0 & 2 \\ 3 & 0 & 3 & 2 to evaluate matrix A?