Question

What is the final sum of 10 + 2 + 0.4 + 0.08 + 0.016... (dividing by 5 every time)?

Answer 1

Answer:

10,2,0.4,0.08 0.016

a=10

d=a2-a1=10-2=8

Sn =?

n=5

Sn=n/2(a+(n-1)d)

Sn=5/2(10+(5-1)8)

Sn=5/2(10+(4)8)

Sn=5/2(10+32)

Sn=5/2(42)

Sn=5/2×2(21)

Sn=5(21)

Sn=105