Saya mohon bantuan... Hitung deret geometri tak hingga Dgn rumus Sn=a/1-r

4) a = 4/7
r = 1/7
Sn = a/1-r
= (4/7)/(1-1/7)
= (4/7)/(6/7)
= 4/6

5. A = 21
R = -1/7
Sn = a/1-r
= 21/1-(-1/7)
= 21/(8/7)
=147/8