\[\boxed{\text{1003\ (1003).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 6x^{3} - 8x^{2} + 3xy - 4y =\]
\[= \left( 6x^{3} + 3xy \right) - \left( 8x^{2} + 4y \right) =\]
\[= 3x \cdot \left( 2x^{2} + y \right) - 4 \cdot \left( 2x^{2} + y \right) =\]
\[= \left( 2x^{2} + y \right)(3x - 4)\ \]
\[2)\ x^{4} - 6x^{2}y + 9y^{2} - 16 =\]
\[= \left( x^{4} - 6x^{2}y + 9y^{2} \right) - 4^{2} =\]
\[= \left( x^{2} - 3y \right)^{2} - 4^{2} =\]
\[= \left( x^{2} - 3y - 4 \right)\left( x^{2} - 3y + 4 \right)\ \]
\[4)\ c^{2} - 2c - b^{2} - 4b - 3 =\]
\[= c^{2} - 2c - b^{2} - 4b - 4 + 1 =\]
\[= \left( c^{2} - 2c + 1 \right) - \left( b^{2} + 4b + 4 \right) =\]
\[= (c - 1)^{2} - (b + 2)^{2} =\]
\[= (c - 1 - b - 2)(c - 1 + b + 2) =\]
\[= (c - b - 3)(c + b + 1)\ \]