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

C1 Polynomials help! Watch

Announcements
    • Thread Starter
    Offline

    0
    ReputationRep:
    10. a) Find the first three terms in the expansion of (1+2x)^10

    I thought it might be 2x^10 + 20x^9 + 90x^9 but I'm not sure.

    b) Use the substitution x = 0.01 and your answer to (a) to find an approximate value for 1.02^10. Give your answer to an appropriate number of decimal places.

    Offline

    12
    ReputationRep:
    (Original post by yesineedhelp)
    10. a) Find the first three terms in the expansion of (1+2x)^10

    I thought it might be 2x^10 + 20x^9 + 90x^9 but I'm not sure.

    b) Use the substitution x = 0.01 and your answer to (a) to find an approximate value for 1.02^10. Give your answer to an appropriate number of decimal places.

    You need to use the binomial theorem/expansion or whathever you may call it. Part b will follow on from there.
    Offline

    0
    ReputationRep:
    Question 1a) (1+2x)^10

    =(10c0 *1) + (10c1 * 1 * 2x) + (10c2 * 1 * 4x^2)

    =1 + (10 * 1 * 2x) + (45 * 1 * 4x^2)

    = 1 + 20x + 180x^2


    Question 1b)

    put 0.01 as x into my equation.

    i think this is right?


    M-G-C-E
    Offline

    2
    ReputationRep:
    (Original post by yesineedhelp)
    10. a) Find the first three terms in the expansion of (1+2x)^10

    I thought it might be 2x^10 + 20x^9 + 90x^9 but I'm not sure.

    b) Use the substitution x = 0.01 and your answer to (a) to find an approximate value for 1.02^10. Give your answer to an appropriate number of decimal places.

    use binomial expansion:
    (1+x)^n
    x=2x
    n=10

    then use formula - 1 +(n)(x) +(n)(n-1)(x)^2/2! +(n)(n-1)(n-2)(x)^3/3! and so on....
 
 
 
  • 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
    Will you be richer or poorer than your parents?
    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
  • 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.