4.4.14. Find a basis for the orthogonal complement of the following subspaces of R4: (a) the set of solutions to -x + 3y - 2z + w = 0; (b) the subspace spanned by (1,2,-1,3)T, (-2,0,1,-2)T, (-1,2,0,1)T; (c) the kernel of the matrix in Exercise 4.4.13c; (d) the coimage of the same matrix.