This question concerns the set S = {v1, v2, v3} of vectors in R3, where v1 = (1, 1, -1), v2 = (1, 3, 4), v3 = (7, -5, 2). (a) Show that S is an orthogonal set. (b) Refer to a result or results from the module that enable you to deduce from part (a) that S is an orthogonal basis for R3. c) Find an expression for the vector (1, 2, 2) as a linear combination of the vectors in the basis S