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Math Help - Complex Numbers...Find x

  1. #1
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    Complex Numbers...Find x

    Solve for x: (3 + 2i) + (4 + xi)= 7 - 5i

    (1) -7
    (2) -3
    (3) 3
    (4) 7
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by magentarita View Post
    Solve for x: (3 + 2i) + (4 + xi)= 7 - 5i

    (1) -7
    (2) -3
    (3) 3
    (4) 7
    3 + 2i + 4 + xi = 7 + (2 + x)i

    now equate real and imaginary parts...
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  3. #3
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    Hi magentarita.

    Its simple math:

    (3 + 2i) + (4 + xi)= 7 - 5i

    // - 3 // -2i

    4+x*i = 4 -7i

    //-4

     x*i = -7i

    // : i

    =>  x = -7\frac{i}{i} = -7

    Kind regards,
    Rapha
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  4. #4
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    what does......

    Quote Originally Posted by Rapha View Post
    Hi magentarita.

    Its simple math:

    (3 + 2i) + (4 + xi)= 7 - 5i

    // - 3 // -2i

    4+x*i = 4 -7i

    //-4

     x*i = -7i

    // : i

    =>  x = -7\frac{i}{i} = -7

    Kind regards,
    Rapha
    In this case, what does the symbol // mean?
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  5. #5
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    ok....

    Quote Originally Posted by Jhevon View Post
    3 + 2i + 4 + xi = 7 + (2 + x)i

    now equate real and imaginary parts...
    7 + (2 + x)i = 7 - 5i

    7 + 2i + xi = 7 - 5i

    7 - 7 + xi = -2i - 5i

    xi = -7i

    x = -7i/i

    x = -7

    Is this correct?
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  6. #6
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    Quote Originally Posted by magentarita View Post
    7 + (2 + x)i = 7 - 5i

    7 + 2i + xi = 7 - 5i

    7 - 7 + xi = -2i - 5i

    xi = -7i

    x = -7i/i

    x = -7

    Is this correct?
    Yes, but it's easier to just say

    Real parts: 7 = 7, correct.

    Imaginary parts: 2 + x = -5 \implies x = -7.
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  7. #7
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    Quote Originally Posted by magentarita View Post
    In this case, what does the symbol // mean?
    It means nothing.
    I just use(d) it to show the steps.
    Don't you know some Programming languages (like Java)? Sometimes you use " // " to comment several lines out.

    Regards,
    Rapha
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  8. #8
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    Thanks

    I want to thank everyone for your reply.
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