Let F be a field and let f be the linear functional on F2 defined by f(x1,x2)=ax1+bx2. For each of the following linear operators T, let g=Ttf, and find g(x1,x2).
(a) T(x1,x2)=(x1,0);
(b) T(x1,x2)=(−x2,x1);
(c) T(x1,x2)=(x1−x2,x1+x2).