Question:
Express each of the following in the form (a + ib):
$\frac{(1-i)^{3}}{\left(1-i^{3}\right)}$
Solution:
Given: $\frac{(1-i)^{3}}{\left(1-i^{3}\right)}$
The above equation can be re-written as
$=\frac{(1)^{3}-(i)^{3}-3(1)^{2}(i)+3(1)(i)^{2}}{\left(1-i \times i^{2}\right)}$
$\left[\because(a-b)^{3}=a^{3}-b^{3}-3 a^{2} b+3 a b^{2}\right]$
$=\frac{1-i^{3}-3 i+3 i^{2}}{[1-i(-1)]}\left[\because i^{2}=-1\right]$
$=\frac{1-i \times i^{2}-3 i+3(-1)}{(1+i)}$
$=\frac{1-i(-1)-3 i-3}{1+i}$
$=\frac{-2+i-3 i}{1+i}$
$=\frac{-2-2 i}{1+i}$
$=\frac{-2(1+i)}{1+i}$
$=-2+0 i$