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Math Help - subbing in x = (u+v)

  1. #1
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    subbing in x = (u+v)

    came across this problem

    x^3+px=q

    sub in x=u+v

    then it says they got this

    u^3+v^3+(3uv+p)(u+v) = q how did it become this? x^3 \Rightarrow u^3+v^3 this makes sense but the (3uv+p)(u+v) doesn't. why isn't it just p(u+v)
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  2. #2
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    Re: subbing in x = (u+v)

    ...

    expand out $(u+v)^3$
    Thanks from Jonroberts74
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  3. #3
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    Re: subbing in x = (u+v)

    oh geez. maybe reading math this late at night is a bad idea. haha
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