i am very sorry as this is an easy question but my confidence is very low. in a text book the author has the following signal and z transform. the signal is, $$f(n) = 2u(n) + 3u(n)$$ the author then goes on to give the z transform as, $$F(z) = 2\frac{z}{z-1} + 3\frac{z}{z-1}$$
surely the signal can be given as $$f(n) = 5u(n)$$
and the transform as $$F(z) = 5\frac{z}{z-1}$$
did i miss something? very sorry but my confidence is so low and i dont get why the author would leave it like this if not for some specific reason that i have missed