Question

If the first term of a geometric sequence is 300 and the third term is 3, find
the sum of the first 25 terms.

Answer 1

Can you find the rate of the sequence from the information you have?

Answer 2

im not sure lol ?

Answer 3

no i dont know how to find it..

Answer 4

thats all the info that was given

Answer 5

So, a geometric sequence is something like this:
1, 2, 4, 8, 16, 32 in wich the rate is 2
Therefore, in general, if you have the first term and the rate you can find any other(an) term by using the following formula:
\[A_{n}=A_{1}r^{n-1}\]
Knowing all of this, can you find the rate now?

Answer 6

the rate pf the sequence isnt given and neither is the last term. all that is given is the first and third. using that formula we could find any term having our rate, but if we dont have a rate how do we find the sum of the first 25 terms?

Answer 7

ohhh nvm i got it

Answer 8

See the formula, you have two terms, and you can put them both there, then the only variable left would be the rate, and you can find it.

Answer 9

ya thanks that works

Answer 10

you're a dollll

Answer 11

Do you know how to continue from here?

Answer 12

yesss i do thanks!