Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    13
    ReputationRep:
    Hello,

    Can anybody explain part iii) of this question (June 2007)?

    I got it all the answers of part i) and ii) correct, but then the mark scheme just stated a substitution of k=1 into the matrix, followed by the usual solving of simultaneous equations with the inverse of A.


    Name:  FP1 matrices.jpg
Views: 153
Size:  47.0 KB
    • Thread Starter
    Offline

    13
    ReputationRep:
    Anybody? :\
    Offline

    0
    ReputationRep:
    if you look at matrix A, and the simultaneous equations, you will notice that the coefficients of x, y and z match the elements of the matrix (when you sub k for 1). so:

    A ( x, y, z ) = ( 1, 12, 3 )
    => (A^-1) A ( x, y, z) = (A^-1) ( 1, 12, 3 )
    => ( x, y, z ) = (A^-1) ( 1, 12, 3)

    so multiply the column vector by A^-1 (inverse of A which is B when you sub for k * (1/ k-n)) and the values of the resulting column vector are your values of x, y and z
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by elliot785)
    if you look at matrix A, and the simultaneous equations, you will notice that the coefficients of x, y and z match the elements of the matrix (when you sub k for 1). so:

    A ( x, y, z ) = ( 1, 12, 3 )
    => (A^-1) A ( x, y, z) = (A^-1) ( 1, 12, 3 )
    => ( x, y, z ) = (A^-1) ( 1, 12, 3)

    so multiply the column vector by A^-1 (inverse of A which is B when you sub for k * (1/ k-n)) and the values of the resulting column vector are your values of x, y and z
    Oh wow, thanks a lot!

    Can not believe I did not see that the first time -_-'
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?

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.