\[\boxed{\text{1017.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ (a + b)^{2}(a - b) -\]
\[- 2ab(b - a) - 6ab(a - b) =\]
\[= (a - b)³\]
\[(a + b)\left( a^{2} - b^{2} \right) - 2ab^{2} +\]
+\(2a^{2}b - 6a^{2}b + 6ab^{2} =\)
\[= (a - b)³\]
\[a^{2} - ab^{2} + a^{2}b - b^{3} +\]
\[+ 4ab^{2} - 4a^{2}b = (a - b)³\]
\[a^{3} + 3ab^{2} - 3a^{2}b - b^{3} =\]
\[= (a - b)³\ \]
\[(a - b)^{3} = (a - b)^{3}\]
\[Что\ и\ требовалось\ доказать.\]
\[\textbf{б)}\ (a + b)(a - b)^{2} +\]
\[+ 2ab(a + b) - 2ab( - a - b) =\]
\[= (a + b)³\]
\[(a - b)\left( a^{2} - b^{2} \right) + 2a^{2}b +\]
\[+ 2ab^{2} + 2a^{2}b + 2ab^{2} =\]
\[= (a + b)³\]
\[a^{3} - ab^{2} - a^{2}b + b^{3} + 4a^{2}b +\]
\[+ 4ab^{2} = (a + b)³\]
\[a^{3} + 3ab^{2} + 3a^{2}b +\]
\[+ b^{3} = (a + b)³\]
\[(a + b)³ = (a + b)³\]
\[Что\ и\ требовалось\ доказать.\]