\[\boxed{\text{615\ (615).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[\textbf{а)}\ 3ab\left( a^{2} - 2ab + b^{2} \right) =\]
\[= 3ab \cdot a^{2} - 3ab \cdot 2ab + 3ab \cdot b^{2} =\]
\[= 3a^{3}b - 6a^{2}b^{2} + 3ab^{3}\]
\[\textbf{б)} - x^{2}y\left( x^{2}y^{2} - x^{2} - y^{2} \right) =\]
\[= - x^{4}y^{3} + x^{4}y + x^{2}y^{3}\]
\[\textbf{в)}\ 2,5a^{2}b\left( 4a^{2} - 2ab + 0,2b^{2} \right) =\]
\(= 10a^{4}b - 5a^{3}b^{2} + 0,5a^{2}b^{3}\)
\[= 2a^{3}x^{4} - 3a^{3}x^{3} + a^{4}x^{2}\]
\[= 63x^{5}y^{3} - 30x^{2}y^{4} - 7x^{3}y^{2}\]
\[= - 7p^{5}q^{7} + 2,1p^{3}q^{8} + 2,8p^{2}q^{9}\]