I think that by factor theorem, z-(5+7i) and z-(5-7i) are factors.

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junior college 2 H2 Maths Singapore

I think that by factor theorem, z-(5+7i) and z-(5-7i) are factors.

Date Posted: 4 years ago

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Eric Nicholas K

4 years ago

If 5 + 7i is a root, then 5 - 7i must be a root as well.

Sum of roots
= 5 + 7i + 5 - 7i
= 10

Product of roots
= (5 + 7i) (5 - 7i)
= 25 + 49
= 74

x2 - 10x + 74 = 0
3x2 - 30x + 222 = 0

so A = -30 and B = 222.

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Date Posted: 4 years ago

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