a -2 b What is the value of the determinant 3 7 -1 when a = -1 and b = 2 4 5 9 Answer: and AXB =C When a = -2, b = 4 and c = 7 what is the value of X1correct to two decimal places? (Show decimal places even if your answer is an integer.) Answer: 4 a b D= 2 C -1 If a = -2, b = 4 and c = 5, what is the the cofactor of D21? Answer: x=[c 6 8 a]y=[b 2 -1 7 ] If a =-5, b = -5 and c = -1 then what does xy equal