Question

Let (x1;x2;x3) and (y1;y2;y3) represent the coordinates with respect to the bases
B1 = f(1;0;0); (0;1;0); (0;0;1)g, B2 = f(1;0;0); (0;1;2); (0;2;1)g. If
Q(X) = x2
1+2x1x2+2x2x3+x2
2+x2
3, find the representation of Q in terms of
(y1;y2;y3).