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Math Help - I'm so lost! Please help.

  1. #1
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    I'm so lost! Please help.

    Okay the paper says multiply by the conjuate

    2+i
    ____ I think I multiply top and bottom by 4+2i but I'm not sure if I do that
    4 +2i or if Im suppose to change the middle sign first or what..? Any advice?
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  2. #2
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    Quote Originally Posted by KeiaBlake View Post
    Okay the paper says multiply by the conjuate

    2+i
    ____ I think I multiply top and bottom by 4+2i but I'm not sure if I do that
    4 +2i or if Im suppose to change the middle sign first or what..? Any advice?
    You multiply top and bottom by the complex conjugate of the denominator: 4 - 2i.
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  3. #3
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    Quote Originally Posted by KeiaBlake View Post
    Okay the paper says multiply by the conjuate

    2+i
    ____ I think I multiply top and bottom by 4+2i but I'm not sure if I do that
    4 +2i or if Im suppose to change the middle sign first or what..? Any advice?
    The conjugate of 4+2i is 4-2i.

    \dfrac{2+i}{4+2i}=\dfrac{(2+i)(4-2i)}{(4+2i)(4-2i)} = \dfrac{8-4i+4i-(-2)}{16-(-4)}=\dfrac{10}{20}=\dfrac12
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