Let W= and v = 3 9 5 V2 = 3 V3 = 6 -5 -18 a) Find a value of c so that we (v, V2, V3). b) Determine if the vectors v1, U2, U3 are linearly independent. c) Add a vector v4 to the previous list so that {v, U2, U3, U4) are linearly independent. Describe the span of {v}