Question:
Evaluate:
(i) $\left(i^{41}+\frac{1}{i^{71}}\right)$
(ii) $\left(i^{53}+\frac{1}{i^{53}}\right)$
Solution:
(i) $\left(i^{41}+\frac{1}{i^{71}}\right)=i^{41}+i^{-71}$
$\Rightarrow i^{4 \times 10+1}+i^{-4 \times 18+1}\left(\right.$ Since $\left.i^{4 n+1}=i\right)$
$\Rightarrow \mathrm{i}^{1}+\mathrm{i}^{1}$
$\Rightarrow 2 \mathrm{i}$
Hence, $\left(i^{41}+\frac{1}{i^{71}}\right)=2 i$
(ii) $\left(i^{53}+\frac{1}{i^{53}}\right)$
$\Rightarrow i^{53}+i^{-53}$
$\Rightarrow i^{4 \times 13+1}+i^{-4 \times 14+3}$ (Since $i^{4 n+1}=i$
$\left.\Rightarrow i^{1}+i^{3} i^{4 n+3}=-1\right)$
$\Rightarrow 0$
Hence, $\left(i^{53}+\frac{1}{i^{53}}\right)=0$