4)y2 4y-4 y-2 y-2

4) $$\frac{y^2}{y - 2} - \frac{4y - 4}{y - 2} = \frac{y^2 - 4y + 4}{y - 2} = \frac{(y - 2)^2}{y - 2} = y - 2.$$

Ответ: $$y-2$$