1. Determine if the linearity property holds for the discrete-time system described by the I/O relationship y[n]=2^x[n] and y[n]=nx[n]. Consider the input signal

   x1[n]=0.8^n,0≤ ???? ≤5 and x2[n] = cos[n],0≤ ???? ≤5. 

   The linearity property holds for a discrete-time system if

   S { a1x1[n] + a2x2[n]} = a1S{x1[n]} + a2S{x2[n]}