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Find all real values for

*r*for which

*r*i is a solution of the equation.

z^4 - 2z^3 + 11z^2 - 18z + 18 = 0

hence, Determine all the solutions of the equations...

I'm not really sure how to tackle questions like this. I subbed in 'ri' for 'z' and worked out r, but it had multiple values, some of which are not solutiuons as listed in the back of the book. Perhaps i did it wrong all together.

A quick guide through the question would help heaps :)

Also

A similar question

Find the real number 'k' such that z=ki is a root of the equation:

z^3 + (2+i)z^2 + (2+2i)z + 4 = 0.

is this basically the same as the earlier question?

Thanks in advance :)