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Math Help - Basic Math Problem

  1. #1
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    Basic Math Problem

    I need help on a question the questions says

    by eliminating Y, find the solution to the Simulataneous Eqautions.

    X(squared)+Y(squared)=25
    Y=X-7

    Thanks in Advance,
    Aslam
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  2. #2
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    Plug x-7 in for y in the first equation so x^2+(x-7)^2=25
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  3. #3
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    Quote Originally Posted by Aslam Anjum View Post
    I need help on a question the questions says

    by eliminating Y, find the solution to the Simulataneous Eqautions.

    X(squared)+Y(squared)=25
    Y=X-7

    Thanks in Advance,
    Aslam
    x^2+y^2 = 25

    As you've stated y=x-7 so we can sub that in for where we see 'y' in the first equation.

    x^2 + (x-7)^2 = 25 \: , \: x^2 + x^2 - 14x + 49 = 25

    2x^2 - 14x + 24 = 0
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  4. #4
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    Thanks for that but I think this is a quadratic as there is space to put two sets of values for X and Y.

    can you please work it out and tell what the answers are so i can check to see if I'm gettting the right answers

    Thanks again,

    Aslam
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  5. #5
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    You can tell us what you get for answers and we'll tell you if you are right. This forum is to help people not to do it for you
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  6. #6
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    Quote Originally Posted by Aslam Anjum View Post
    Thanks for that but I think this is a quadratic as there is space to put two sets of values for X and Y.

    can you please work it out and tell what the answers are so i can check to see if I'm gettting the right answers

    Thanks again,

    Aslam
    Well you can solve that equation to find x and from there find y:

    2x^2 - 14x + 24 = 0

    Divide by 2: x^2 - 7x+12 = 0

    I can see that this factorises to (x-4)(x-3) = 0

    therefore either x-4=0 or x-3=0 and therefore x = 4 or x=3.

    We then put these back into y = x-7

    y = 4-7 = -3 or y = 3-7 = -3.

    Our solutions are therefore x=4, y=-3 or x=3, y=-4. There are two pairs of answers for this
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  7. #7
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    thanks for that i didnt get anything close to that I started using the other eqaution i cant tell which equation to use when i see the questions.

    thanks for the help,

    Aslam
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