Hey there! Sign in to join this conversationNew here? Join for free

Maths - Geometric sequences C2. Question 8 mixed exercise Watch

    • Thread Starter
    Offline

    2
    ReputationRep:
    Hello,

    A sequence of numbers U1, U2...Un is given by the formula Un = 3(2/3)^n - 1

    Find the values of u1 u2 and u3

    Which I did.

    When i cam to the second part I thought that to find the common ratio I do it by the usual method of dividing u1/u2 which is wrong obviously...

    I just found it a bit tricky to do because that seems like the thing you would do - does anyone understand what I mean?

    The common ratio is 2/3 - I suppose I am just frustrated that that just didnt come to mind as I was reading it and trying to do part b which asks

    show that the sum of the first u1 - u15 = -9.014

    Anyway explain it better to me than the book is??

    Thanks
    • Community Assistant
    Offline

    18
    ReputationRep:
    Community Assistant
    It's U2/U1
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brussels sprouts
    Help with your A-levels

    All the essentials

    The adventure begins mug

    Student life: what to expect

    What it's really like going to uni

    Rosette

    Essay expert

    Learn to write like a pro with our ultimate essay guide.

    Uni match

    Uni match

    Our tool will help you find the perfect course for you

    Study planner

    Create a study plan

    Get your head around what you need to do and when with the study planner tool.

    Study planner

    Resources by subject

    Everything from mind maps to class notes.

    Hands typing

    Degrees without fees

    Discover more about degree-level apprenticeships.

    A student doing homework

    Study tips from A* students

    Students who got top grades in their A-levels share their secrets

    Study help links and info

    Can you help? Study help unanswered threadsRules and posting guidelines

    Sponsored content:

    HEAR

    HEAR

    Find out how a Higher Education Achievement Report can help you prove your achievements.

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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

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