jumlah tak hingga deret geometri adalah 25/4 , rationya 1/5 tentukan a

jawab

S~ = 25/4
r = 1/5

s~ = a/(1 - r)
a = s ~ ( 1 - r)
a = 25/4 ( 1 - 1/5)
a = 25/4 ( 4/5)
a = 5

25/4 = a/(1-1/5)
25/4 = a/(4/5)
a = 25/4 x 4/5
a = 25/5
a = 5