# Complex numbers

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#1
Hi I am currently doing some past papers and I've come across a complex numbers question. Ive attached the question together with a solution. However I was wondering if anyone could please check whether the solution is right and if it is explain to me where I go wrong.
From what I know, j^2 = -1 Therefore (j^2)(3.2)(8.1) would create a negative value of -25.92 however in the solution to this question it creates a positive value? Same goes to j(-4.9)(8.1) that should create a negative value of -39.69 however in the solution its positive.
Am I doing something wrong here and i should make these positive? If so, then why?

Sorry, for some reason I can't upload a cropped pic from my phone, it's the example (iv).

Thank you for any help
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2 years ago
#2
(Original post by panda7190)
Thank you for any help
Yes, you're correct. The two parts you mention are in error in the given solution.
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#3
Thank you so much I was quite stressed out that I was doing something wrong
0
2 years ago
#4
(Original post by panda7190)
Hi I am currently doing some past papers and I've come across a complex numbers question. Ive attached the question together with a solution. However I was wondering if anyone could please check whether the solution is right and if it is explain to me where I go wrong.
From what I know, j^2 = -1 Therefore (j^2)(3.2)(8.1) would create a negative value of -25.92 however in the solution to this question it creates a positive value? Same goes to j(-4.9)(8.1) that should create a negative value of -39.69 however in the solution its positive.
Am I doing something wrong here and i should make these positive? If so, then why?

Sorry, for some reason I can't upload a cropped pic from my phone, it's the example (iv).

Thank you for any help
Yes, the solution is wrong

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