////////////////////////////////////////////////////////////////
//
//     http://www.planetquantum.com/Solve/Level1/Den13/Page16.txt
//
////////////////////////////////////////////////////////////////

Generator:
(C (^ _Pi 1/2) _E 6 7 2)

Problem:
(= (cdot #[[17 72 45 38 50 90 55]
           [16 2 72 98 16 74 83]
           [34 11 45 18 27 97 54]
           [94 56 12 23 87 12 82]
           [13 80 77 89 85 29 11]
           [28 45 91 3 21 81 37]]
         #[[x_1] [x_2] [x_3] [x_4] [x_5] [x_6] [x_7]])
   #[[27] [18] [28] [18] [28] [45]])

Solution:
(= #[[x_1] [x_2] [x_3] [x_4] [x_5] [x_6] [x_7]]
   #[[-146908257780]
     [-70209397247]
     [45646879937]
     [-83182562613]
     [134534979067]
     [-36999539539]
     [95682806752]])