ГДЗ по алгебре 7 класс Макарычев Задание 661

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\[\textbf{а)}\ x^{2} + 8x = 0\]

\[x(x + 8) = 0\]

\[x = 0\ \ или\ \ x + 8 = 0\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 8\]

\[Ответ:x = 0;\ \ x = - 8.\]

\[\textbf{б)}\ 5x^{2} - x = 0\]

\[x(5x - 1) = 0\]

\[x = 0\ \ или\ \ 5x = 1\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = \frac{1}{5} = 0,2\]

\[Ответ:x = 0;\ \ x = 0,2.\]

\[\textbf{в)}\ 6y^{2} - 30y = 0\]

\[6y(y - 5) = 0\]

\[y = 0\ \ \ или\ \ \ \ y - 5 = 0\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ y = 5\]

\[Ответ:y = 0;\ \ y = 5.\]

\[\textbf{г)}\ 3x^{2} - 1,2x = 0\]

\[1,2x(2,5x - 1) = 0\]

\[x = 0\ \ или\ \ \ 2,5x = 1\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 0,4\]

\[Ответ:x = 0;\ \ x = 0,4.\]

\[\textbf{д)}\ 6x^{2} - 0,5x = 0\]

\[0,5x(12x - 1) = 0\]

\[x = 0\ \ или\ \ \ \ 12x - 1 = 0\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = \frac{1}{12}\]

\[Ответ:x = 0;\ \ x = \frac{1}{12}.\]

\[\textbf{е)}\ \frac{1}{4}y^{2} + y = 0\]

\[y\left( \frac{1}{4}y + 1 \right) = 0\]

\[y = 0\ \ \ \ или\ \ \ \frac{1}{4}y = - 1\]

\(y = - 4\)

\(Ответ:y = 0;\ \ y = - 4.\)

\[\textbf{ж)}\ x - 10x^{2} = 0\]

\[x(1 - 10x) = 0\]

\[x = 0\ \ или\ \ 1 = 10x\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 0,1\]

\[Ответ:x = 0;\ \ x = 0,1.\]

\[\textbf{з)}\ 6x - 0,2x^{2} = 0\]

\[x(6 - 0,2x) = 0\]

\[x = 0\ \ или\ \ \ \ 6 = 0,2x\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 30\]

\[Ответ:x = 0;\ \ x = 30.\]

\[\textbf{и)}\ \ y^{2} + \frac{2}{3}y = 0\]

\[y\left( y + \frac{2}{3} \right) = 0\]

\[y = 0\ \ \ \ \ или\ \ \ \ y = - \frac{2}{3}\]

\[Ответ:y = 0;\ \ y = - \frac{2}{3}.\]