Turn on thread page Beta
    • Thread Starter
    Offline

    2
    ReputationRep:
    ok the question is
    n
    ∑ (4- r/2)
    6

    so the terms are are 1 + 0.5 + 0 -0.5 ......4-n/2

    so i tried to evaluate it

    1 + 4-n/2= 5-n/2

    then multiply by no. of pairs n/2

    5-n/2 x n/2 = 10-n

    i thought that would be right

    but the answer is 1/4(n-5)(10-n)

    how?
    • Thread Starter
    Offline

    2
    ReputationRep:
    need an asap anyone please...its bugging me
    Offline

    1
    ReputationRep:
    The number of pairs isn't n/2, because you're starting at 6, so it's (n-5)/2. Still not sure how you get the answer though.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Libertine)
    The number of pairs isn't n/2, because you're starting at 6, so it's (n-5)/2. Still not sure how you get the answer though.
    thanx

    ive got it to 1/2 (n-5)(10-n)

    but dont know where they 1/4 came from!?! this is frustrating
    Offline

    1
    ReputationRep:
    (5-n/2) x (n-5)/2

    = (5n-25)/2 - (n²-5n)/4

    = (10n - 50)/4 - (n²-5n)/4

    = (15n - n² - 50)/4

    = (1/4) x (n-5)(10-n)
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Libertine)
    (5-n/2) x (n-5)/2

    = (5n-25)/2 - (n²-5n)/4

    = (10n - 50)/4 - (n²-5n)/4

    = (15n - n² - 50)/4

    = (1/4) x (n-5)(10-n)
    thank you soo much
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 19, 2005

University open days

  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
  • Bournemouth University
    Undergraduate Open Day Undergraduate
    Sat, 17 Nov '18
Poll
Black Friday: Yay or Nay?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Equations

Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.