SOS!!! Алгебра-царица наук)) не могу одолеть, блин))))))

4) $\frac{(x+y)^{2}-4xy}{x+y}* \frac{(y-x)^{2}+4xy}{y-x}= \frac{(x^{2}-2xy+y^{2})(x^{2}+2xy+y^{2})}{(x+y)(y-x)}= \frac{(x-y)^{2}(x+y)^{2}}{-(x+y)(x-y)}= =-(x-y)(x+y)=-(x^{2}-y^{2})=y^{2}-x^{2}$
2) $\frac{a^{2}-a^{2}+b^{2}}{a(a-b)}* \frac{a-b}{2b}= \frac{b}{2a}$

1) $\frac{b}{a+b}* \frac{(a-b)(a+b)}{b^{2}}= \frac{a-b}{b}$
$\frac{2(x-y)}{y}* \frac{y^{2}}{(x-y)(x+y)}= \frac{2y}{x+y}$
$-\frac{2^{3}(a^{2})^{3}}{b^{3}}=- \frac{8a^{6}}{b^{3}}$
$\frac{3aba^{2}}{b}= 3a^{3}$