Part C: Linearity
My definition of linearity in terms of systems is:
A system whose output combined with a linear shift is equivalent to the output if the linear shift is on the input of the system.
An example of a linear system is:
$ x(t) = t + 3 $
To prove this:
$ Y_1(t) = A*x(t) = Z_1(t) Y_2(t) = X(At) = Z_2(t) Z_1(t) = Z_2(t) $
for any number A
