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## Homework Statement

Under the section of complex number, i faced 2 questions which i couldn't answer... Here they go...

-Show that x=1-2i is a root of the equation x

^{3}-3x

^{2}+7x-5=0. Hence, find all the roots of the equation.

-Express http://img832.imageshack.us/img832/7916/msp180019e92f47ie4d5afg.gif [Broken] in the form a+ib, where a>0.

## Homework Equations

for both question, ''i'' represents imaginary number

## The Attempt at a Solution

I tried both for hour but couldn't solve them...

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