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Math Help - algebra equation

  1. #1
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    algebra equation

    <br />
\sqrt{x+a} + \sqrt{x - a} = \sqrt{2} \sqrt{x+7}<br />


    i need it simplified (it is multiple choice) but as much as i may try i cant rember how to do this type of problem plz help thank you.


    if u want the 5 choices i have..i can give them...but it owuld do no good because i still want to know how to solve the problem (show the work if you can)
    Last edited by jcube69; September 28th 2008 at 04:14 PM. Reason: able to show true form of equation
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  2. #2
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    Quote Originally Posted by jcube69 View Post
    i have no idea how to make a radical around somthing so ill do my best and place # where the radical begins -.-

    #(x+a) + #(x-a)=#2*#(x+7)


    in words i guess it would be [radical] x plus a [/radica] + [radical] x minus a [/radical] = [radical]2[/radical] times [radical] x plus 7[/radical]


    i need it simplified (it is multiple choice) but as much as i may try i cant rember how to do this type of problem plz help thank you.


    if u want the 5 choices i have..i can give them...but it owuld do no good because i still want to know how to solve the problem (show the work if you can)
    So are you trying to solve this equation...

    \sqrt{x+a} + \sqrt{x - a} = \sqrt{2} \sqrt{x+7} ???

    P.S. the code is, after you've written math in square brackets,
    sqrt{expression under square root sign}, and then write /math in square brackets.
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  3. #3
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    yes exactly how it is
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  4. #4
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    Quote Originally Posted by Prove It View Post
    So are you trying to solve this equation...

    \sqrt{x+a} + \sqrt{x - a} = \sqrt{2} \sqrt{x+7} ???

    P.S. the code is, after you've written math in square brackets,
    sqrt{expression under square root sign}, and then write /math in square brackets.
    \sqrt{x+a} + \sqrt{x - a} = \sqrt{2} \sqrt{x+7}

    Squaring both sides gives

    x + a + 2\sqrt{x+a}\sqrt{x-a} + x - a = 2(x+7)

     2x + 2\sqrt{(x+a)(x-a)} = 2x + 14

     2\sqrt{x^2 - a^2} = 14

     \sqrt{x^2 - a^2} = 7

     x^2 - a^2 = 49

     x^2 = a^2 + 49

     x = \pm \sqrt{a^2 + 49} .
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  5. #5
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    thank you very much

    i ahd the right idea but did a step wrong ^.^

    thanks again^.^
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