Question

What is the sum of the first five terms of the geometric sequence in which a1 = 5 and r = 1/5?

Answer 1

I'm thinking 1/125...

but idk for sure... :( is that the answer?? 1/125??

**no answer choices!!

Answer 2

do u get this??? :)

Answer 3

do you know the formula for geometric sequences?

Answer 4

and then i did this...
a1 = 5

a2 = 5 x 1/5 = 1

a3 = 1 x 1/5 = 1/5

a4 = (1/5) x (1/5) = 1/25

a5 = (1/25) x (1/5) = 1/125

so thats how i got 1/125... idk if i did it right.. is that correct??

Answer 5

@Brittni0605 @jim_thompson5910 :) :)

Answer 6

you can use the formula, or add up those 5 terms you just found

Answer 7

kk so did i do it right??? like the math part above??

so i add all them together right?? or is my answer just 1/125??

Answer 8

agreed with @jim_thompson5910

Answer 9

wait so i add theM??? a1 = 5

a2 = 5 x 1/5 = 1

a3 = 1 x 1/5 = 1/5

a4 = (1/5) x (1/5) = 1/25

a5 = (1/25) x (1/5) = 1/125

those 5 terms?? :D

Answer 10

yep

Answer 11

so i need to convert to the same denominator right?

Answer 12

or use the formula

S = a[ (1-r^n)/(1-r) ]

S = 5[ (1-(1/5)^5)/(1-1/5) ]

S = ???

Answer 13

S=6.224279835???

is that right???

oh and i need to write it in fraction form,... :/ forgot to say that!!