Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

NatalieLove Group Title

What is the sum of the arithmetic sequence 137, 125, 113 …, if there are 38 terms?

  • 2 years ago
  • 2 years ago

  • This Question is Closed
  1. myininaya Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Do you see that the numbers are increasing by 8?

    • 2 years ago
  2. NatalieLove Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    yes

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

    i would do it the old school way and keep subtracting 12 until you get 38 terms, then add lol

    • 2 years ago
  4. myininaya Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    \[\sum_{i=0}^{37}(137+8i)=137+8(0)+\sum_{i=1}^{37}(137+8i)\] Now use \[\sum_{i=1}^{n}i=\frac{n(n+1)}{2} \text{ and } \sum_{i=1}^{n}c=cn\]

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

    Im still not getting the correct answer

    • 2 years ago
  6. Zarkon Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    whay are people using d=8

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

    *why

    • 2 years ago
  8. NatalieLove Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    i dont know im gonna guess

    • 2 years ago
  9. FoolForMath Group Title
    Best Response
    You've already chosen the best response.
    Medals 3

    Whenever you need to find the sum of an arithmetic series use this formula: \[ \frac n 2 \left( 2a+ (n-1) \right)\times d) \tag{1}\] a= first term n= number of terms d= common difference Here, \(n= 38, a = 137 \) and \( d = -12\). Substituting these in \((1)\), and assuming my algebra is right you answer should be \(-3230 \)

    • 2 years ago
  10. NatalieLove Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I know but the answer does not show up in the multiple choose

    • 2 years ago
  11. FoolForMath Group Title
    Best Response
    You've already chosen the best response.
    Medals 3

    @NatalieLove: Revert if you need help in proving that formula.

    • 2 years ago
  12. NatalieLove Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    We are doing the same steps the test its incorrect. It does not show up as a choose Thank You

    • 2 years ago
  13. FoolForMath Group Title
    Best Response
    You've already chosen the best response.
    Medals 3

    Glad to help :)

    • 2 years ago
  14. myininaya Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    omg lol I said increasing by 8 and then continue to think the thingy was increasing by 8 sometimes i wonder about myself lol

    • 2 years ago
    • Attachments:

See more questions >>>

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.