deret bilangan geometri 1/12+1/6+1/3 brpa 5 suku pertama

r = 1/6:1/12
= 12/6 = 2
Sn = a.r^n-1÷r-1
S5 = 1/12.2^5 -1÷2-1
= 1/12.32 -1÷1
=32/12 -1
=32/12 - 12/12
=20/12
=5/3
jd jml 5 suku pertama adl 20/12 atau 5/3