Jawabanmu

2014-06-24T20:08:50+07:00
U2 = 11 atau a + b = 11  ............................(1)
S4 = 52
Sn = (n/2)(2a + (n-1)b)
S4 = (4/2)(2a + (4-1)b)
52 = 2(2a + 3b)
2a + 3b = 26 ............................................(2)
2a + 2b = 22 -..........................................(1)
         b = 14
a + b = 11 ⇔ a + 14 = 11 ⇔ a = 11-14 = -3
S8 = (8/2)(-6 + 7(14))
     = 4(-6 + 98)
     = 4(92)
    = 368
kok jwaban nya gag ada di pilihan ganda nya ya?
saya yg salah b = 4, a+b=11 atau a+4=11 berarti a = 7, S8=4(14+7(4)) terus S8 =4(14+28) = 4(42)=168 oh yaa ada di option B.
makasih :)
sama-sama