Consider the set Qs = {1, i, j, k} having 8 elements with an operation satisfying the following relations i.ij.j = kk = -1 ijk, j.ki, ki = j (-1) (-1) = +1 (a) Show that (28.) is a group with +1 as its identity element. (Qs is called the group of quaternions.) 4 (b) Is (Q8..) an abelian group? Explain why or why not. (c) Show that every subgroup of (Q8,-) is normal.