Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

katiebugg

  • 3 years ago

The sum of an arithmetic series is 1356 and the first term is -1. If the common difference is 5, how many terms are in the sequence?

  • This Question is Closed
  1. ash2326
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @katiebugg Sum of n terms is given 1356 First term \(a_1=-1\) and common difference=5 we know that sum to n terms is given as \[S_n=\frac{n}{2}(a_1+a_n)\] \(a_n\) is the last term Do you get till this?

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

    yess

  3. ash2326
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    we know \(a_n\) is given as \[a_n=a_1+(n-1)d\] d=common difference n=no. of terms so sum will become \[S_n=\frac n2 (a_1+a_1+(n-1)d)\] now pluigin the numbers here and post what do you get, will you?

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

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy