упростите выражение:2ав-4в 4в-------------------- __ -------а(в квадр.)-4а+4 а-2

1Вариант

$\frac{2ab-4b}{a^{2}-4a+4}-\frac{4b}{a-2}=\frac{2b(a-2)}{(a-2)^{2}}-\frac{4b}{a-2}=\frac{2b(a-2)}{(a-2)(a-2)}-\frac{4b}{a-2}=\frac{2b}{a-2}-\frac{4b}{a-2}=\frac{2b-4b}{a-2}=\frac{-2b}{a-2}=-\frac{2b}{a-2}$

2 Вариант

$\frac{2ab-4b}{a^{2}-4a+4}-\frac{4b}{a-2}=\frac{2ab-4b}{(a-2)^{2}}-\frac{4b}{a-2}=\frac{2ab-4b}{(a-2)(a-2)}-\frac{4b}{a-2}=\frac{2ab-4b-4b(a-2)}{(a-2)(a-2)}=\frac{2ab-4b-4ab+8b}{(a-2)(a-2)}=\frac{(2ab-4ab)+(-4b+8b)}{(a-2)(a-2)}=\frac{-2ab+4b}{(a-2)(a-2)}=\frac{-2b(a-2)}{(a-2)(a-2)}=\frac{-2b}{a-2}=-\frac{2b}{a-2}$