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by **honest_denverco09** on Wed Apr 15, 2009 2:48 am

I am rewriting this quotient into the form (a + bi), but i am stuck in the signs of the imaginary and the real number parts.

I have : (3 + 5i)/(6i)
I did multiply this fraction by (6i) for both of Numerator and Denominator. As a result, i had ( (-1/2)i + 5/6 ).
But computer's answer is opposite to my answer 's signs. He got ( (1/2)i - 5/6 ).

I would like to ask where are my mistakes ?

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by **Martingale** on Wed Apr 15, 2009 2:55 am

honest_denverco09 wrote:I am rewriting this quotient into the form (a + bi), but i am stuck in the signs of the imaginary and the real number parts.

I have : (3 + 5i)/(6i)
I did multiply this fraction by (6i) for both of Numerator and Denominator. As a result, i had ( (-1/2)i + 5/6 ).
But computer's answer is opposite to my answer 's signs. He got ( (1/2)i - 5/6 ).

I would like to ask where are my mistakes ?

I get what you get

$\frac{3+5i}{6i}=\frac{3+5i}{6i}\cdot\frac{6i}{6i}=\frac{18i+30i^2}{36i^2}=\frac{18i+30(-1)}{36(-1)}=\frac{18i}{-36}+\frac{-30}{-36}=-\frac{1}{2}i+\frac{5}{6}$

though I would have just multiplied by $\frac{i}{i}$

by **honest_denverco09** on Thu Apr 16, 2009 12:03 am

Thanks!

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Signs in the complex number: (3 + 5i)/(6i)

Signs in the complex number: (3 + 5i)/(6i)

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Re: Signs in the complex number: (3 + 5i)/(6i)