Problem 1: We define the determinant of a matrix in general to be
det(A)=\sum_(j=1)^n (-1)^(1+j)a_(1j)det(A_(1j))
Given this information, find the determinant of the following matrices ANALYTICALLY! (Do not use a calculator). (a)
[[1,2],[3,6]]
(c)
[[a,b],[0,d]]
(e)
[[1,-1,0],[0,2,1],[-1,-2,1]]
(b)
[[1,2],[0,6]]
(d)
[[1,0,0],[2,3,4],[1,-1,2]]
(f)
[[a,b,c],[0,e,f],[0,0,i]]
Problem 2: Are the following matrices invertible? Explain. (a)
[[1,2],[3,6]]
(c)
[[a,b],[0,d]]
(e)
[[1,1,2],[1,-2,-1],[1,1,2]]
(b)
[[1,2],[0,6]]
(d)
[[a,b],[c,d]]
(f)
[[a,b,c],[0,e,f],[0,0,i]]