3. {2+1+2+2=7 points Show all work!) (5.) Calculate the determinant of A by using the enqzansim across column 3, where A = 1 2 3 _4 3 _ 7 5 9 (b) Is the matrix A invertible? Why a; why not? (c) Find 3-1, where B = ['75 Es . (Entries must be fractional) (d) Solve Br = [88] by using an inverse