Question

What is the sum of the first five terms of the geometric sequence in which a1= 10 and r=1/2

Answer 1

Answer:19.375

Explanation:

a=10

r=1/2=0.5

Sn=a(1-r^n)/(1-r)

S5=10(1-(0.5)^5)/(1-0.5)

S5=10(1-0.03125)/(0.5)

S5=(10 x 0.96875)/(0.5)

S5=9.6875 ➗ 0.5

S5=19.375