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    Gosh, okay this seems like a simple question but:

    Attachment 728880

    Why is the (2k) [outside the bracket] to the power of 2
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    Post it please so we can help.
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    (Original post by CorpusLuteum)
    Gosh, okay this seems like a simple question but:


    Why is the (2k) outside the bracket to the power of 2
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    I cannot see the attachment but you're asking why is 2k in bracket? Well, (x+2k)^2 when expanded will yield an extra (2k)^2 term which you don't, hence you subtract it.
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    (Original post by RDKGames)
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    Okay I think it worked now?
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    (Original post by CorpusLuteum)
    Gosh, okay this seems like a simple question but:

    Attachment 728880

    Why is the (2k) outside the bracket to the power of 2
    Name:  Capturesds.PNG
Views: 13
Size:  3.3 KB
    actually attach your attachment !!
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    (Original post by CorpusLuteum)
    Okay I think it worked now?
    yes, it worked, now.

    do you know how to complete the square?

    Can you complete the square and solve

    x^2 - 4x -1 = 0 ??
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    x^2+4kx-k = 0 --> (x+2k)^2-(2k)^2-k=0.

    E.g. x^2+6x+10 --> (x+3)^2 - 3^2 + 10 --> (x+3)^2 + 1. It's how completing the square works; you generate an extra term that should be subtracted.
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    (Original post by CorpusLuteum)
    Okay I think it worked now?
    Because (x+2k)^2 = x^2+4kx+4k^2 but you only want the first two terms, hence x^2+4kx = (x+2k)^2-4k^2, but 4k^2 = (2k)^2 hence that's where it comes from.
 
 
 
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