\[\left( m^{2} - m - 1 \right)\left( m^{2} + m + 1 \right) =\]
\[= - \left( m + 1 - m^{2} \right)\left( m + 1 + m^{2} \right) =\]
\[= - \left( (m + 1)^{2} - \left( m^{2} \right)^{2} \right) =\]
\[= - \left( m^{2} + 2m + 1 - m^{4} \right) =\]
\[= m^{4} - m^{2} - 2m - 1.\]