$$ x^{5}=u $$
$$ u^{2}+u+1=0 $$
$$(u+ \frac{1}{2})^2+ \frac{3}{4}=0 \Rightarrow u+ \frac{1}{2}= \pm i \frac{ \sqrt{3} }{2} $$
$$(u+ \frac{1}{2}+ \frac{i \sqrt{3} }{2})(u+ \frac{1}{2}- \frac{i \sqrt{3} }{2}) $$
$$( x^{5} + \frac{1}{2}+ \frac{i \sqrt{3} }{2})(x^{5}+ \frac{1}{2}- \frac{i \sqrt{3} }{2}) $$دقت شود که i ثابت اعداد مختلط میباشد