Решите пожалуйста. (Сложно)

1)

$\displaystyle ( \frac{1}{a}+ \frac{1}{b})*((a+b)^2- \frac{a^3-b^3}{a-b})=$

$\displaystyle = \frac{b+a}{ab}*(a^2+2ab+b^2- \frac{(a-b)(a^2+ab+b^2)}{a-b})=$

$\displaystyle \frac{b+a}{ab} *(a^2+2ab+b^2-a^2-ab-b^2)= \frac{b+a}{ab}*ab=b+a$

2)

$\displaystyle ( \frac{1}{7a}+ \frac{1}{2a})* \frac{a^2}{4}= \frac{2a+7a}{14a^2}* \frac{a^2}{4}= \frac{9a}{14a^2}* \frac{a^2}{4}= \frac{9}{56}*a$

$\displaystyle \frac{9}{56}*(-2.8)= \frac{9}{56}* \frac{-28}{10}= \frac{-9}{20}$