5. Let V be a vector space, and let X1, X2, .. ., Xx E V. 5(a) Prove that if either x1 - 0 or xj+1 6 span{x1, ..., x; } for some j - 1, 2, ...,k -1, then x1, x2, . ..; xx is linearly dependent. [4 marks]5. Let V be a vector space, and let X1, X2, ..., Xk E V. 5(b) Prove that if x1, x2, ..., xx is linearly dependent, then either x1 - 0 or x;+1 6 span{x1, ..., x;} for some j - 1, 2, .. .. k - 1. [4 marks]