Jawabanmu

2014-01-18T11:51:57+07:00
2 4 8 16 32 64 128
loncatan setiap bilangn dikalikan 2

Jadi, 2+4+8+16+32+64+128 = 254
1 1 1
2014-01-18T14:04:30+07:00
Sn = a(r^n-1)/ r-1
S7 = 2 (2^7-1/ 2-1
S7 = 2( 128-1)/1
S7 = 2(127)
S7 = 254