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Math Help - pairs of numbers

  1. #1
    Member Rimas's Avatar
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    pairs of numbers

    Find the ordered pair of numbers (x,y) for which 123x+321y=345 and 321x+123y=543
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  2. #2
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    Hello, Rimas!

    Find the ordered pair of numbers (x,y) for which:
    . . 123x + 321y .= .345
    . . 321x + 123y .= .543
    Just solve the system of equations . . .
    . . You do know how, right?

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  3. #3
    Member Rimas's Avatar
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    no i dont
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Rimas View Post
    Find the ordered pair of numbers (x,y) for which 123x+321y=345 and 321x+123y=543
    We have:
    123x+321y=345 .........................(1)
    321x+123y=543 .........................(2)

    Divide the first equation by 123 and the second by 321 to obtain:

    x + 2.6098y = 2.8049 ..................(3) = (1)/123
    x + 0.3832y = 1.6916 ..................(4) = (2)/321

    Now subtract equation (4) from equation (3) to get rid of the x, and then solve for y

    => 2.2266y = 1.1133 ....................(3) - (4)
    => y = 1.1133/2.2266 = 1/2

    Plug in the value you got for y into any one of the first equations to find x

    but 123x + 321y = 345
    => 123x + (1/2)(321) = 345
    => 123x = 345 - 321/2 = 184.5
    => x = 184.5/123 = 3/2

    Verify your answers by plugging in the numbers you got into the left hand side of both equations and see that you get the correct right hand side. These answers were correct, so:

    The numbers (x,y) are (3/2 , 1/2)
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