For problems asking for a sketch, be sure to label heights and times. Show intermediate steps of your work. 1. Difference Equation Problems: (a) Show that the first difference system y[n] = y[n1] x[n] is equivalent to the running summation formula y[n] = Pnk= x[k]. (b) Show that the first difference system with scaled feedback by a: y[n] = ay[n 1] x[n], is equal to the summation formula y[n] = Pk=0 akx[n k]