x2 - 5x + 143 = 0
Using the quadratic formula: a = [ 5 + i·sqrt(547) ] / 2 and b = [ 5 - i·sqrt(547) ] / 2
a - 1 = [ 5 + i·sqrt(547) ] / 2 - 1 = 5/2 + i·sqrt(547)/2 - 1 = 3/2 + i·sqrt(547)/2
b - 1 = [ 5 - i·sqrt(547) ] / 2 - 1 = 5/2 - i·sqrt(547)/2 - 1 = 3/2 - i·sqrt(547)/2
(a - 1)(b - 1) = [ 3/2 + i·sqrt(547)/2 ] · [ 3/2 - i·sqrt(547)/2 ] = 9/4 - i2·547/4 = 139