2 6). 1-x²+2xy-y² 6) (2x²-4x) 1-x+y (8-4x) 2

5) $$ \frac{1-x^2+2xy-y^2}{1-x+y} = \frac{1-(x^2-2xy+y^2)}{1-x+y} = \frac{1-(x-y)^2}{1-x+y} = \frac{(1-(x-y))(1+(x-y))}{1-x+y} = \frac{(1-x+y)(1+x-y)}{1-x+y} = 1+x-y $$

Ответ: $$1+x-y$$