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Math Help - Simple Algebra Problem

  1. #1
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    Simple Algebra Problem

    Hi all,

    I have a simple algebra problem that has been bugging me

    "....the product of two numbers is 30. Their average is 6. What are the two number?"

    I know this problem is easy; but, I cant seem to work it out.

    I pretty much started out like this :

    (a) let's say the numbers are X and Y

    (b) so, average is 6. Meaning : (x+y) / 2 = 6

    (c) Hence, x+y = 12

    (d) Product : x * y = 30

    (e) So : (x+y=12) and (x*y=30)

    (f) Next, I decided to equate both expressions :

    10(x+y) = 120

    4(x*y) = 120


    (g) So : 10(x+y) = 4xy


    And, this is where I got stumped
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  2. #2
    MHF Contributor Unknown008's Avatar
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    Equating them wasn't much use since you didn't eliminate any of the numbers...

    What you could do is:

    x + y = 12

    xy = 30

    So,

    x = 12 - y

    Substitute in the other equation;

    y(12 - y) = 30

    Can you finish it?
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  3. #3
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    Now, I feel SOOOOOOOOOOO stupid

    Thanks )))
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  4. #4
    MHF Contributor Unknown008's Avatar
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    You're welcome
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