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Mathematics 11 Online
OpenStudy (emilyjones284):

Find the cube roots of -8+0i

OpenStudy (anonymous):

Is -2 one of the answers

OpenStudy (whpalmer4):

Well, one of them is quite easy: -2 -2*-2*-2 = -8

OpenStudy (whpalmer4):

But for extra points, Daniel the 7th grader, how many cube roots are there of -8?

OpenStudy (whpalmer4):

(I don't think I could have answered that question when I was in 7th grade!)

OpenStudy (emilyjones284):

I thought the answer would just be -2 because I'm not sure what else to do...but I hope there's not more to it

OpenStudy (whpalmer4):

Oh, there is, my dear, there is :-)

OpenStudy (emilyjones284):

Oh noooooooooooooooooooooooooooooooooo :(

OpenStudy (whpalmer4):

|dw:1395290534530:dw|

OpenStudy (whpalmer4):

So the root young Daniel found is the -2 on the left. The roots are always symmetrically arranged, so the other two are complex conjugates, and are located at \(a\pm bi\)|dw:1395290706292:dw|

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