Correct and clear! - Ronny Wijaya
Looks pretty good to me! -- Kathleen Schremser
This is a good definition and the use of the mathematical definition makes it even better. -- Aishwar Sabesan
This definition works for me. -- Derek Hopper
One problem with the definition of a non-linear system. It should be worded as "...system is called "Non-Linear" if there exists constants $ \alpha, \beta \! $ (part of the Complex Number domain) and there exists inputs $ x_1(t), x_2(t)\! $ (or $ x_1[n], x_2[n]\! $) yielding..." It only takes one set of constants/ inputs to prove a system non-linear. -- Jeff Kubascik