ГДЗ по математике 6 класс Мерзляк Решаем устно параграф 26

\[\boxed{\mathbf{Решаем}\mathbf{\ }\mathbf{устно}\mathbf{\ }\mathbf{параграф}\mathbf{\ }\mathbf{26}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[\boxed{\mathbf{1.}}\]

\[1)\ 18\pi\ :9 = 2\pi\]

\[2)\ 18\ \pi \cdot 5 = 90\pi\]

\[\boxed{\mathbf{2.}}\]

\[10\pi = 2\pi r\]

\[r = \frac{10\pi}{2\pi} = 5\ см.\]

\[2)\ S_{кр} = \pi r² = \pi \cdot 5² = 25\pi\ см².\]

\[Ответ:\ 25\pi\ см².\]

\[\boxed{\mathbf{3.}}\]

\[1)\ 16\pi = \pi r^{2}\]

\[r^{2} = \frac{16\pi}{\pi} = 16\]

\[r = 4\ см.\]

\[2)\ l = 2\pi r = 2\pi \cdot 4 = 8\pi\ см.\]

\[Ответ:\ 8\pi\ см.\]

\[\boxed{\mathbf{4.}}\]

\[1)\ 3x + 5x + 7x = 60\]

\[15x = 60\]

\[x = 4.\]

\[2)\ 19x - 12x = 4,9\]

\[7x = 4,9\]

\[x = 0,7.\]

\[3)\ 8x + 3x + 1,6 = 1,93\]

\[11x = 1,93 - 1,6\]

\[11x = 0,33\]

\[x = 0,03.\]

\[4)\ 14x - 4x - 2,8 = 11,2\]

\[10x = 11,2 + 2,8\]

\[10x = 14\]

\[x = 1,4.\]