Question Number 133201 by Tojiboyeva Kamolahon last updated on 19/Feb/21
$$\sqrt{\mathrm{81}} \\ $$
Answered by MJS_new last updated on 20/Feb/21
$$−\mathrm{3}^{\mathrm{2}} \mathrm{e}^{\mathrm{i}\pi} \\ $$
Commented by MJS_new last updated on 20/Feb/21
$$\mathrm{sorry}\:\mathrm{forgot}\:\mathrm{the}\:“\:^{\mathrm{2}} '' \\ $$
Answered by john_santu last updated on 20/Feb/21
$$\sqrt{\mathrm{81}}\:=\:−\sqrt{\mathrm{81}}\:×\left(−\mathrm{1}\right)\: \\ $$$$\:=\:−\mathrm{9}\:\left(\mathrm{cos}\:\pi+{i}\:\mathrm{sin}\:\pi\:\right) \\ $$$$\:=−\mathrm{9}\:\mathrm{e}^{{i}\pi} \: \\ $$