If $(x+i y)=\left(\frac{1+i}{1-i}\right)^3-\left(\frac{1-i}{1+i}\right)^3$, then the true statement among…

If $(x+i y)=\left(\frac{1+i}{1-i}\right)^3-\left(\frac{1-i}{1+i}\right)^3$, then the true statement among the following is
  1. $x < y$
  2. $x>y$
  3. $x \neq 0$
  4. $x=y$

Solution

Given $(\mathrm{x}+\mathrm{iy})=\left(\frac{1+\mathrm{i}}{1-\mathrm{i}}\right)^3-\left(\frac{1-\mathrm{i}}{1+\mathrm{i}}\right)^3$ $ \begin{aligned} & \Rightarrow x-i y=\left\{\left(\frac{1+i}{1-i} \times \frac{1+i}{1+i}\right)-\left(\frac{1-i}{1+i} \times \frac{1-i}{1+i}\right)\right\} \\ & =\frac{1}{8}[-8 i-8 i] \\ & =-2 i \\ & x+i y=0+(-2) i \\ & \Rightarrow x>y \end{aligned} $

Asked in: AP EAMCET 2022 (06 Jul Shift 1)

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