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Math Help - Find 'i'

  1. #1
    Junior Member
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    Find 'i'- where i^2 = -1


    The answer should be -7/5 - 17i/10 but somehow I couldn't figure it out.



    The answer should be -2 -3i/2 but I always get -2 +3i/2 for my answer. Help please?


    i is an imaginary number. That is i^2 = -1
    Last edited by delicate_tears; February 7th 2009 at 11:33 PM.
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  2. #2
    Member smmmc's Avatar
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    when you say find 'i' do you mean make i the subject? because the answer is -7/5 - 17i/10, which has 'i' in it .
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  3. #3
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    \frac {8-3i-4-6i}{2+4i}=\frac {4-9i}{2+4i}=a+bi\rightarrow 4-9i=(2+4i)(a+bi)=2a+4ai+2bi-4b= 2a-4b+(4a+2b)i So 4=2a-4b and -9=4a+2b. Can you continue from here?
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