Fuente TeX:

\langle (x,y,z,t), (2, -1, 0, 0) \rangle = 2x -y \\ \langle (x,y,z,t), (0, 0, 4, -2) \rangle =3 \frac{z-t}{2} + \frac{z+t}{2}= 2z-t