Turn on thread page Beta
    • Thread Starter
    Offline

    15
    ReputationRep:
    http://mathsathawthorn.pbworks.com/f/FP1Jun06.pdf
    Could someone teach me how to start on q4?
    The last time I did geometric series was in core 2 but ive forgot them:/
    Is it a,ar, ar^2?
    Offline

    16
    ReputationRep:
    Form of a geometric series:

    a + ar + ar^2

    We know that the common ratio, r, is 2, so:

    a + 2a + 4a.

    This means that the first root is equal a, the second, 2a, and the third, 4a.
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by English-help)
    http://mathsathawthorn.pbworks.com/f/FP1Jun06.pdf
    Could someone teach me how to start on q4?
    The last time I did geometric series was in core 2 but ive forgot them:/
    Is it a,ar, ar^2?
    Yes the roots would be a, 2a, 2^2a such that a>0 in order for them to be positive.

    Then just equate \displaystyle \sum \alpha \beta = 56 from your knowledge of roots of cubic polynomials, and solve for a.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by RDKGames)
    Yes the roots would be a, 2a, 2^2a such that a>0 in order for them to be positive.

    Then just equate \displaystyle \sum \alpha \beta = 56 from your knowledge of roots of cubic polynomials, and solve for a.
    Okayy good
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 25, 2017

2,705

students online now

800,000+

Exam discussions

Find your exam discussion here

Poll
Who is going to be the top scorer of the World Cup in 2018?
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

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.