Question Number 178725 by ComplexPrime last updated on 20/Oct/22
$$\mathrm{Let}\:{a}\:\mathrm{be}\:\mathrm{a}\:\mathrm{positive}\:\mathrm{number}.\:\mathrm{Then} \\ $$$$\sqrt{{a}}=\sqrt{\left(−{a}\right)\left(−\mathrm{1}\right)}=\sqrt{−{a}}\centerdot{i}=\sqrt{{a}\left(−\mathrm{1}\right)}\centerdot{i}=\sqrt{{a}}\centerdot{i}^{\mathrm{2}} =−\sqrt{{a}} \\ $$$$\mathrm{Where}\:\mathrm{is}\:\mathrm{the}\:\mathrm{mistake}? \\ $$