Let W be the subset of F3/7 defined by W= {[x1] 3
{[x2] ∈ F |x1+5x2=0}
{[x3] 19
Give part of the proof that W is a subspace of Fig, in the following steps: (a) Explain why 0 ∈ W. (b) Suppose x,y ∈ W. Explain why x+y ∈ W.