Question

What are the values of a 1 and r of the geometric series? 1 + 3 + 9 + 27 + 81 a 1 = 1 and r = one-third a 1 = one-third and r = 1 a 1 = 1 and r = 3 a 1 = 3 and r = 1

Answer 1

a₁ = 1 and r = 3

Explanation:

`1+3+9+27+81\\\\a_1=1,\ a_2=3,\ a_3=9,\ a_4=27,\ a_5=81\\\\r=(a_(n+1))/(a_n)\Rightarrow r=(a_2)/(a_1)=(a_3)/(a_2)=(a_4)/(a_3)=(a_5)/(a_4)\\\\r=(3)/(1)=(9)/(3)=(27)/(9)=(81)/(27)=3`

Answer 2

Good evening ,

Answer:

a₁ = 1

r = 3

Explanation:

Since it’s a geometric series then

a₁ = 1 ( because 1 is the first term of the series)

3/1 = 9/3 = 27/9 = 81/27 = 3 then r=3.

:)