Q-4: [5+5 marks] a) Find the value(s) of c for which the following vectors vi --- = 0 0 V2 = 0 1 ---| ,V3 = = and V4 are linearly independent. -1 1 b) Express the vector (-1,5,-6) in Ras a linear combination of (2,0,7), (2,4,5) and (2, -12,13)