Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta

PLZ help me with maths coursework watch

Announcements
    • Thread Starter
    Offline

    2
    ReputationRep:
    hi,ppl. i m studying in year 10, doing my gcses. in maths we r doing coursework on stacking boxes. it is about sequences and nth term.i m stuck on the bit where i have to explain and make a link between the formula i have obtained and drawing which are in 3 dimension.
    I am attaching drawings of my stacks in 3D where n=3 n=4
    Plz help me. I dont know how to expain in terms of n, where n^2 and n antd etc are in the stack. the cubis formula for 3D is
    un=4n^2 - 7n + 4
    Attached Images
  1. File Type: pdf maths coursework black and white.pdf (53.5 KB, 98 views)
    Offline

    0
    ReputationRep:
    Ill gladly help u, but this goddam computer im sitting on don't have acrobat reader! upload a .doc or other file instead and ill have a peak. (did almpost the same kind of problem not too long ago)
    Offline

    1
    ReputationRep:
    by obversation we can see the term does not 'go up' by a constant, therefore we are dealing with a quadratic (an ax^2)
    we can see that when n=1, Un=1
    n=2, Un=6
    n=3, Un= 19

    when n=1, a*n^1 + b*n + c = 1 => a+b+c=1
    when n=2, a*n^2 + b*2n + c = 6 => 4a + 2b + c = 6
    when n=3, a*n^3 + b*3n + c = 19 => 9a + 3b + c = 19

    three equations, 3 unknowns, I'll let someone else (or you!) work it out. It should work out as Ive done it here but i cba to type it up now.

    Rev
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Revelation)
    by obversation we can see the term does not 'go up' by a constant, therefore we are dealing with a quadratic (an ax^2)
    we can see that when n=1, Un=1
    n=2, Un=6
    n=3, Un= 19

    when n=1, a*n^1 + b*n + c = 1 => a+b+c=1
    when n=2, a*n^2 + b*2n + c = 6 => 4a + 2b + c = 6
    when n=3, a*n^3 + b*3n + c = 19 => 9a + 3b + c = 19

    three equations, 3 unknowns, I'll let someone else (or you!) work it out. It should work out as Ive done it here but i cba to type it up now.

    Rev
    lol, i ve done it. it is in the attachment look in it. btw here u need to use cubic formula un = an^3 + bn^2 + cn + d
    i Ve found the formula. But now i need to explain it in terms of n^3, n^2 and n.
 
 
 
Poll
Do you agree with the proposed ban on plastic straws and cotton buds?

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.