Jawabanmu

2014-02-19T17:59:47+07:00
U10 = 45
u4 + u9 + u10 = 84
u4 + u9 + 45 = 84
u4 + u9 = 39

n = 19
a = -52
b = 13
sn = 19/2 {2(-52)+13(18)}
sn = 19/2 {-104 + 234}
sn = 19/2 x 130
sn = 1235