Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

koli123able

  • 2 years ago

In a G.P. , the first term is 7, the last term is 448, and the sum is 889. Find the common ratio and the number of terms.

  • This Question is Closed
  1. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    use an=a1*r^(n-1)

  2. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    where an=48 and a1=7

  3. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    *448

  4. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    it is coming r^(n-1)=64

  5. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    then i used the sum formula Sn=\[Sn =\frac{ a[r^n-1) }{ r-1 }\]

  6. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    exactly...now you got two equations in two unknowns...so solve for r and n

  7. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i am stuck here

  8. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    where??tell me the second one

  9. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[127=\frac{ r^n-1 }{ r-1 }\]

  10. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    r comes out to be 2.isn't it??

  11. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    The answer should come r=2 and n=7

  12. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    yeah hold on lemme write

  13. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok

  14. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1356937412146:dw|

  15. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    ^from here you can get r=2....then put r=2 in first equation to get n

  16. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    got it??

  17. koli123able
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes

  18. stgreen
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    good

  19. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.