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Jnr Cert Honours student has brain freeze ! help

  • 09-11-2011 8:07pm
    #1
    Spook_ie
    Registered Users, Registered Users 2 Posts: 10,896 ✭✭✭✭


    Ok, I'm a bit stuck on a question for my maths HomeWork. It is a form of simultaneous equation.
    The question is as follows:

    The sum of four times one number and three times the second number is 61.
    If twice the first number less the second number is 13, find the numbers.

    The answers in the back of my book are 7 and 10 however I keep getting the incorrect answer. :confused:

    Any help would be much appreciated. :)


Comments

  • #2
    ray giraffe
    Registered Users, Registered Users 2 Posts: 338 ✭✭ray giraffe


    Spook_ie wrote: »
    The sum of four times one number and three times the second number is 61.
    If twice the first number less the second number is 13, find the numbers.

    The answers in the back of my book are 7 and 10

    4x+3y=61
    2x-y=13

    Maybe you could multiply the second equation by 3, so you have 3y in the first and -3y in the second.


  • #3
    Spook_ie
    Registered Users, Registered Users 2 Posts: 10,896 ✭✭✭✭Spook_ie


    Thanks a million for the quick reply! I understand completely now! :D


  • #4
    bnt
    Registered Users, Registered Users 2 Posts: 13,077 ✭✭✭✭bnt


    Another way I like would involve rearranging the second equation to read y=2x-13. Then, in the first equation, replace y with (2x-13) and solve for x.

    You are the type of what the age is searching for, and what it is afraid it has found. I am so glad that you have never done anything, never carved a statue, or painted a picture, or produced anything outside of yourself! Life has been your art. You have set yourself to music. Your days are your sonnets.

    ―Oscar Wilde predicting Social Media, in The Picture of Dorian Gray



  • #5
    Spook_ie
    Registered Users, Registered Users 2 Posts: 10,896 ✭✭✭✭Spook_ie


    Thanks BNT - I appreciate all the help


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