\[\boxed{\text{916\ (916).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ a² + 2a + 2 =\]
\[= a^{2} + 2a + 1 + 1 =\]
\[= (a + 1)^{2} + 1 \geq 0 \Longrightarrow при\ \]
\[любом\ n.\]
\[\textbf{б)}\ 2x² - 2xy + y^{2} =\]
\[= x^{2} - 2xy + y^{2} + x^{2} =\]
\[= (x - y)^{2} + x^{2} \geq 0 \Longrightarrow при\ \]
\[любых\ значениях\ \text{x\ }и\ y.\]