Question

Упростить и подставить

Answer 1

$\frac{4ab^2}{ab^2-2b} = \frac{4ab^2}{b(ab-2)} =\left. \frac{4ab}{ab-2} \right|_{a=\sqrt5-1, b=\sqrt5+1} = \frac{4(\sqrt5-1)(\sqrt5+1)}{(\sqrt5-1)(\sqrt5+1)-2} = \\ = \frac{4(5-1)}{(5-1)-2} = 8.$