Question Number 47068 by 143jesus last updated on 04/Nov/18
$$\left(\mathrm{a}−\mathrm{b}\right)^{\mathrm{2}} \\ $$
Answered by ajfour last updated on 04/Nov/18
$$=\:\left({a}−{b}\right)\left({a}−{b}\right) \\ $$$$=\:{a}\left({a}−{b}\right)−{b}\left({a}−{b}\right) \\ $$$$=\:{a}^{\mathrm{2}} −{ab}−{ba}+{b}^{\mathrm{2}} \\ $$$$=\:{a}^{\mathrm{2}} −\mathrm{2}{ab}+{b}^{\mathrm{2}} \:. \\ $$