Factorise :

x² - y² - 2x + 2y

x² - y² - 2x + 2y

Using the formula

[∵ (x² - y²) = (x + y)(x - y)]

= (x² - y²) - (2x - 2y)

= (x - y)(x + y) - 2(x - y)

= (x - y)((x + y) - 2)

= (x - y)(x + y - 2)

Hence,x² - y² - 2x + 2y = (x - y)(x + y - 2)