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Math Help - [SOLVED] Expand and Simplify

  1. #1
    coolman21
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    [SOLVED] Expand and Simplify

    5(1 - xy)(1 + xy)
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by coolman21 View Post
    5(1 - xy)(1 + xy)
    You should know the difference of two squares factorisation: a^2-b^2=(a-b)(a+b), then recognise that is what you need with a=1 and b=xy to get:

    <br />
5(1 - xy)(1 + xy) =5(1-x^2y^2)<br />

    RonL
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  3. #3
    Newbie
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    Smile Expand and simplify

    Quote Originally Posted by coolman21 View Post
    5(1 - xy)(1 + xy)
    expanding
    5(1 - xy)(1 + xy)
    (5-5xy)(1 + xy)
    5*1+5*xy-5xy*1-(5xy)(xy)
    5+5xy-5xy-5x^2y^2

    simplifying
    5-5x^2y^2
    5-5(xy)^2
    5(1-(xy)^2)

    But if you know the formula mentioned in the other post, you can save yourself some of this trouble.

    I am showing all the steps here (just in case) since the problem said "expand and simplify"
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