ГДЗ по алгебре 9 класс Макарычев Задание 797

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\[\textbf{а)}\ 4x - 5x^{2} < 0\]

\[x(4 - 5x) < 0\]

\[x(5x - 4) > 0\]

\[x \in ( - \infty;\ 0) \cup (0,8;\ + \infty).\]

\[{б)\ 9x² \leq - 5x }{9x^{2} + 5x \leq 0}\]

\[x(9x + 5) \leq 0\]

\[x \in \left\lbrack - \frac{5}{9};0 \right\rbrack.\]

\[\textbf{в)}\ \ 6x² - x - 35 > 0\]

\[D = 1 + 840 = 841 = 29^{2}\]

\[x_{1,2} = \frac{1 \pm 29}{12};\]

\[x_{1} = 2,5;\ \ \ x_{2} = - 2\frac{1}{3}.\]

\[(x - 2,5)\left( x + 2\frac{1}{3} \right) > 0\]

\[x \in \left( - \infty;\ - 2\frac{1}{3} \right) \cup (2,5; + \infty).\]