\[\boxed{\text{398\ (398).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\(а)\ (x + 1)^{2}\)
\[\textbf{б)}\ a^{2} + b^{2}\]
\[\textbf{в)}\ m^{2} - n^{2}\]
\[\textbf{г)}\ (m - n)^{2}\]
\[\textbf{д)}\ 2 \cdot x^{2} \cdot y^{2}\]
\[\textbf{е)}\ 2 \cdot a^{3} \cdot b^{2}\]