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# AQA FP1 - Complex Numbers watch

1. Hey guys, been trying to figure out this question for a while and can't seem to get it. I've done the first part of the question, getting p = -8 and q = 9, and checking the answers that looks right.

However I'm kinda stuck on part B now. The sum of roots I got was 3-7i by doing -b/a. I don't know if that's right and to be honest, I have no idea where to go from there.

Can anybody give me a hint or some other way I could find the answer? Any help would be appreciated.

Question:

2. Sum of the roots is 3 + 7i, I'll assume you made a typo. If not, reply back.

You're given that one root is 2 + 5i. If we call the other root z', then

2+5i + z' = 3 + 7i... find z'...

3. I haven't checked your answer to part (a) so I'll assume it's correct.

For part (b) you know that (where are the roots), but you know that one of the roots is equal to , so must be... [you do this bit].

As for the reason why this isn't the complex conjugate, you should know this. Otherwise, think about when you would expect the roots to be conjugate. [All else failing, consult your textbook; that or someone will probably jump in and tell you anyway, but it's much more fun to find out for yourself.]
4. After looking at it again, I just realised why , sorry I was being a little slow. Thanks for your help guys :P

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Updated: September 26, 2010
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