Part C: Linearity
A linear system is one that given inputs into a system, the sum of the outputs are equivalent to the outputs had the inputs been summed prior to being put through the system.
Example 1: Linear y(t)= 7*t
x1(t) -->|System|--> y1(t)= 7*t
|-->(y1 + y2)--> z =14*t
x2(t) -->|System|--> y2(t)= 7*t
likewise
x1(t) + x2(t) = 2*x1(t)
2*x1(t) -->|System|--> y1(t)= 14*t
Example 2: Non-linear y[n]=x[n]^2
x1[n] -->|System|--> y1[n]= x1[n]^2
|--> (y1 + y2) --> z = x1[n]^2 + x2[n]^2
x2[n] -->|System|--> y2[n]= x2[n]^2
but
(x1[n]+x2[n]) -->|System|--> y[n] = (x1[n]+x2[n])^2
