Question

How (α-β)2=α2+β2-4αβ?

Answer 1

$(\alpha - \beta ) {}^{2} = \alpha {}^{2} + \beta {}^{2} - 4 \alpha \beta \\ = > \alpha {}^{2} + \beta {}^{2} - 2 \alpha \beta = \alpha {}^{2} + \beta {}^{2} - 4 \alpha \beta \\ = >$