Karldahemster
Student
- Joined
- Dec 16, 2016
- Messages
- 89
- Gender
- Male
- HSC
- 2018
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You can definitely solve it that way, but if the marker is strict, you may not receive full marks for not using the directive "hence".
Oh yeah, I didn't even notice the "hence" (or look at part (i)).You can definitely solve it that way, but if the marker is strict, you may not receive full marks for not using the directive "hence".
To do (ii), since you showed that -2i is a root of z^3-8i=0, it follows from the Factor Theorem that (z+2i) is a factor.
Therefore z^3-8i=(z+2i)(z^2+Az+4) , where A can be found from equating coefficients of z^2.
Then find the roots of the quadratic to find the remaining roots of z^3=8i.