\[\boxed{\text{906\ (906).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ x^{4} - 25y^{2} =\]
\[= (x^{2} - 5y)(x^{2} + 5y)\]
\[\textbf{б)}\ 4b² - 0,01c^{6} =\]
\[= (2b - 0,1c^{3})(2b + 0,1c^{3})\]
\[\textbf{в)}\ 8a³ + c³ =\]
\[= (2a + c)(4a^{2} - 2ac + c^{2})\]
\[\textbf{г)}\ x^{9} - 27 =\]
\[= (x^{3} - 3)(x^{6} + 3x^{3} + 9)\]
\[\textbf{д)}\ 9ab² - 16ac^{2} =\]
\[= a\left( 9b^{2} - 16c^{2} \right) =\]
\[= a(3b - 4c)(3b + 4c)\]
\[\textbf{е)} - 20xy^{3} + 45x^{3}y =\]
\[= 5xy\left( 9x^{2} - 4y^{2} \right) =\]
\[= 5xy(3x - 2y)(3x + 2y).\]