Jawabanmu

2014-05-03T12:21:39+07:00
{1,2},{1,3},{1,4},{1,5},{1,6},{2,3},{2,4},{2,5},{2,6},{3,4},{3,5},{3,6},{4,5},{4,6},{5,6}
jadi banya himpunanya 15

2014-05-03T12:57:31+07:00
5P2 = 5! / (5-2)! = (5 x 4 x 3!) / 3!
                             = 5 x4
                             = 20