The complex number has modulus 2 and argument . It is also given that .
- (i)
Given that is an integer, find in terms of , giving your answer in the form .
- (ii)
Hence, find the smallest two positive integers such that is real and negative.
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Worked solution
2(i)
1. Express $z^n$ in exponential form.
2. Express the conjugate $w^*$ in exponential form.
3. Evaluate the quotient $\frac{z^n}{w^*}$.
2(ii)
1. Determine the polar form of the expression using the result from part (i).
From part (i), we establish the exponential forms:
2. Set up the condition for the complex number to be real and negative.
For a complex number to be real and negative, its argument must be an odd multiple of . Therefore, we equate the argument to where :
3. Solve the argument equation for the smallest two positive integers $n$.
Dividing the entire equation by and multiplying by :
Since we require to be a positive integer (), we take the smallest non-negative integer values for :
When ,
When ,
and
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