\[\left( x^{3}y^{2} - 1 \right)\left( 1 + x^{3}y^{2} \right) =\]
\[= \left( x^{3}y^{2} - 1 \right)\left( x^{3}y^{2} + 1 \right) =\]
\[= \left( x^{3}y^{2} \right)^{2} - 1 =\]
\[= x^{6}y^{4} - 1.\]