ГДЗ по алгебре 9 класс Макарычев Задание 231

\[\boxed{\text{231}\text{\ (231)}\text{.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[y = ax^{2}\]

\[\textbf{а)}\ ax^{2} \geq 0\ \ \ при\ \ a \geq 0;\]

\[\textbf{б)}\ \ ax^{2} \leq 0\ \ при\ \ a \leq 0\text{.\ }\]

\[\boxed{\text{231.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]

\[\textbf{а)}\ 13 \cdot (5x - 1) - 15 \cdot (4x + 2) < 0\]

\[65x - 13 - 60x - 30 < 0\]

\[5x - 43 < 0\ \]

\[x < 8,6.\]

\[\textbf{б)}\ 6 \cdot (7 - 0,2x) - 5 \cdot (8 - 0,4x) > 0\]

\[42 - 1,2x - 40 + 2x > 0\]

\[0,8x + 2 > 0\]

\[0,8x > - 2\]

\[x > - 2,5.\]