SOLUTION: I am having problems fiquiring out how i(1+i)^3 *(1-i) is equal to -4. I am required to show work... When I type the equation into my calculator it comes out -4. How so? Thanks,

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Question 115318: I am having problems fiquiring out how i(1+i)^3 *(1-i) is equal to -4. I am required to show work... When I type the equation into my calculator it comes out -4. How so?
Thanks,
Mike
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
having problems fiquring out how i(1+i)^3 *(1-i) is equal to -4
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Expand:
i[1^3+3i+3i^2+i^3]*(1-i)
= i[1 + 3i -3 -i]*(1-i)
= i[-2+2i](1-i)
= -2i[1-i](1-i)
= -2i[1-2i-1]
= -2i[-2i]
= -4
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Cheers,
Stan H.