Jawabanmu

2014-02-27T19:51:46+07:00
Un= 1/2n(n-3)
U12=1/2x12(12-3)
     =54
U8=1/2x8(8-3)
     =20

U12-U8= 54-20=34
2014-02-27T19:53:10+07:00
U12= 1/2*12 (12-3) = 6*9 = 54 u8= 1/2*8 (8-3) = 4*5 = 20 u12-u8= 54-20 = 34