please do the question handwritten

Please do the question handwritten 1. Decide which of the following subsets U of the vector space F 3 are subspaces. Either show that it is a subspace or give an example that it is not a. U = {(x1, x2, x3) : x1 + x2 + x3 = 42}; b. U = {(x1, x2, x3) : x1 + 2x2 + 3x3=0}