Jawabanmu

2014-02-07T19:44:16+07:00
U3 = 14
14 = a + 2b

U7 = 26
26 = a + 6b

Dieliminasi:
a + 6b = 26
a + 2b = 14 -
4b = 12
b = 3

lalu disubsitusi:
a + 2b = 14
a + 2(3) = 14
a + 6 = 14
a = 14-6
a = 8

maka S18 = 18/2(2(8) + 17(3))
= 9(16+51)
=9(67)
s18 = 603
3 4 3