Discussing some of the properties as to when a matrix is invertibe Linear Algebra 2-5-29

Introduction to Linear Algebra
Strang 4th edition
2-5-29
True or false (with a counterexample if false and a reason if true):
(a) A 4 by 4 matrix with a row of zeros is not invertible.
(b) Every matrix with 1's down the main diagonal is invertible.
(c) If A is invertible then A-I and A2 are invertible.