Question

Sum of the series with last term a7 =234,375 and common ratio r=5

Answer 1

series is 15, 75, 375, 1875, 9375, 46875, 234375

Explanation:

r=5

an = 234,375

n = 7

a1 = ?

a1 = an /rn-1

a1 = 234,375 /57-1

a1 = 15

a2 = 15*5 = 75

a3 = 15*25 = 375

a4 = 15*125 = 1875

a5 = 15*625 = 9375

a6 = 15*3125 = 46, 875

a7 = 15*15,625 = 234,375

Hence series is 15, 75, 375, 1875, 9375, 46875, 234375