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Question: Express 15-20i/1-2i in a+bi form.

 

I tried multiplying both sides by 1 + 2i, and got ((15-20i)(1+2i))/5

 

then i simplified that to 9i + 12.

 

but it says i got it wrong. i double checked my simplifaction steps and I didn't have a problem with that.

 

can somebody help me out?

 Feb 1, 2020
edited by Guest  Feb 1, 2020
 #1
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I assume the question is really

Question: Express (15-20i)/(1-2i ) in a+bi form.          Brackets are necessary!

 

\(\frac{15-20i}{1-2i}\\ =\frac{15-20i}{1-2i}*\frac{1+2i}{1+2i}\\ =\frac{15-20i+30i+40}{1+4}\\ =\frac{55-10i}{5}\\ =11-2i\\\)

 

 

Note: I have not checked my answer.

 Feb 1, 2020

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