further maths quesiton Watch

ihatehannah
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https://qualifications.pearson.com/c...e_20130128.pdf

u kno 5a, mark scheme says two of the solutions are 3 plus 5i or 3 minus 5 i, but isent it 3 plus 10 i or 3 minus 10i??? is the mark scheme wrong
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kkboyk
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(Original post by ihatehannah)
https://qualifications.pearson.com/c...e_20130128.pdf

u kno 5a, mark scheme says two of the solutions are 3 plus 5i or 3 minus 5 i, but isent it 3 plus 10 i or 3 minus 10i??? is the mark scheme wrong
Nope, you are wrong. If you solve it by completing the square or by using quadratic formula, you will encounter a square root of a number (which has both a positive and also a negative solution).
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TheConfusedMedic
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(Original post by ihatehannah)
https://qualifications.pearson.com/c...e_20130128.pdf

u kno 5a, mark scheme says two of the solutions are 3 plus 5i or 3 minus 5 i, but isent it 3 plus 10 i or 3 minus 10i??? is the mark scheme wrong
I don't actually do further maths, but I have seen it somewhere before that root -1 = i, so I will try and deduce an answer lol:
x^2 - 6x + 34 = 0
(x-3)^2 - 9 + 34 = 0
(x-3)^2 = -25
x-3 = root-25 (from here onwards it is pure guesswork)
x-3 = root25 * root-1
x-3 = +-5i
x = 3 +- 5i (??)
Spoiler:
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also, just wondering, are you taking further maths early or something because I have seen you on a lot of GCSE threads?
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