\[\boxed{\text{867.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ \left( x^{2} + 4xy - y^{2} \right)(2y - x) = 2x²y - x^{3} + 8xy^{2} - 4x^{2}y - 2y^{3} + y^{2}x =\]
\[= - x^{3} - 2x^{2}y + 9xy^{2} - 2y^{3}\]
\[\textbf{б)}\ (3 - a)\left( a^{3} - 4a^{2} - 5a \right) = 3a³ - 12a^{2} - 15a - a^{4} + 4a^{3} + 5a^{2} =\]
\[= - a^{4} + 7a^{3} - 7a^{2} - 15a\]
\[\textbf{в)}\ \left( a^{2} - 4ab + b^{2} \right)(2a - b) = 2a³ - 8a^{2}b + 2ab^{2} - a^{2}b + 4ab^{2} - b^{3} =\]
\[= 2a^{3} - 9a^{2}b + 6ab^{2} - b^{3}\]
\[\textbf{г)}\ (x - p)\left( x^{2} + px + p^{2} \right) = x³ + px² + p²x - px^{2} - p^{2}x - p^{3} = x^{3} - p³\ \]