Math 115

Review Session - Starts at 230 minutes.

[Mr_i_o]

Please note there I made a mistake yesterday for the following problem at 45:29-48:25. Although it can be true that if A and B are invertible I’ll then (A+B) is invertible, it is not generally true. Here is a counter example :

A=[ 1 0; 0 1], B=[0 1; 1 0]. The det(A)=/0 and det(B)=/0 but the det(A+B)=0.