Решебник по алгебре 7 класс Мерзляк Задание 319

\[\boxed{\text{319\ (319).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

Пояснение.

Решение.

\[1)\ \left( 2a^{2} - 5a + 7 \right) + \ *\ = 5\]

\[* = 5 - \left( 2a^{2} - 5a + 7 \right)\]

\[* = 5 - 2a^{2} + 5a - 7\]

\[* = - 2a^{2} + 5a - 2.\]

\[2)\ \left( 2a^{2} - 5a + 7 \right) + \ * = 0\]

\[* = 0 - \left( 2a^{2} - 5a + 7 \right)\]

\[*\ = 0 - 2a^{2} + 5a - 7\]

\[*\ = - 2a^{2} + 5a - 7.\]

\[3)\ \left( 2a^{2} - 5a + 7 \right) + \ *\ = a^{2}\]

\[*\ = a^{2} - (2a^{2} - 5a + 7)\]

\[*\ = a^{2} - 2a^{2} + 5a - 7\]

\[*\ = - a^{2} + 5a - 7.\]

\[4)\ \left( 2a^{2} - 5a + 7 \right) + \ *\ = - 2a\]

\[*\ = - 2a - \left( 2a^{2} - 5a + 7 \right)\]

\[*\ = \ - 2a - 2a^{2} + 5a - 7\]

\[* = - 2a^{2} + 3a - 7\text{.\ }\]