Question

Use the formula for the sum of the first n terms of a geometric sequence to solve. Find the sum of the first four terms of the geometric sequence: 2, 10, 50, . . . .

A. 312

B. 62

C. 156

D. 19

Answer 1

@amorfide

Answer 2

do the same thing as before, you start it, I will correct you where needed

Answer 3

label, what is a? what is r? what is n?

Answer 4

i dont really know im sorry

Answer 5

A is the first term of any sequence
R is the ratio

to get R you have to do the second term divided by the first term, or third term divided by the second term, or any term divided by the term before it
this gives you your ratio

n is the number of terms you are adding up

Answer 6

you should be able to do this now

Answer 7

a = 2 r = 5 n =3 ?

Answer 8

you want the first 4 terms, not the first 3

Answer 9

o ok

Answer 10

The common ratio is 5, so multiply the 3rd by 5 and that gives you the 4th term. Then just add them

Answer 11

a = 2 r = 5 n = 4

Answer 12

Luigi read her question. It says use the formula

Answer 13

girl ninja, those are right, now stick them in the formula

Answer 14

whats the formula again if you don't mind

Answer 15

write this down on paper, or you probably won't remember it...