exercise11
=====
       x =   1  -2   4   6  -5   8  10
       n =  -4  -3  -2  -1   0   1   2

exercise11a
=====
   x1(n) =   3  -6  10  22 -23  12  41 -18 -16   6  -5   8  10
       n =  -6  -5  -4  -3  -2  -1   0   1   2   3   4   5   6

exercise11b
=====
   x2(n) =   5  -6  12  46  -1  23  76  52  18 -15  24  30
       n =  -9  -8  -7  -6  -5  -4  -3  -2  -1   0   1   2

exercise11c
=====
   x3(n) =   0   0   0   0  10  -8 -40  36 -20 -16  10   0
       n =  -8  -7  -6  -5  -4  -3  -2  -1   0   1   2   3

exercise11d
=====
   x4(n) =   0   0   0   0  -0  -0   2   3  -1  15   0  26  54   0   0   0   0   0   0   0   0
       n = -10  -9  -8  -7  -6  -5  -4  -3  -2  -1   0   1   2   3   4   5   6   7   8   9  10

exercise11e
=====
   x5(n) =   0   1   0   3  12  16  22  55  54  37  80  50
       n =  -4  -3  -2  -1   0   1   2   3   4   5   6   7