\[\boxed{\mathbf{110}\mathbf{9}\mathbf{\text{.\ }}Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ \sqrt{x} = 2\]
\[x = 4\]
\[Ответ:x = 4.\ \ \ \ \]
\[2)\ \sqrt{x} = \frac{1}{4}\]
\[x = \frac{1}{16}\]
\[Ответ:x = \frac{1}{16}.\]
\[3)\ \sqrt{x} - 3 = 0\]
\[\sqrt{x} = 3\]
\[x = 9\]
\[Ответ:x = 9.\]
\[4)\ 2\sqrt{x} - 7 = 0\]
\[\sqrt{x} = \frac{7}{2}\]
\[x = \frac{49}{4}\]
\[x = 12,25\]
\[Ответ:x = 12,25.\]
\[5)\ \sqrt{x} + 5 = 0\]
\[\sqrt{x} = - 5\]
\[Ответ:корней\ нет.\]
\[6)\frac{1}{4}\sqrt{x} + 5 = 0\]
\[\frac{1}{4}\sqrt{x} = - 5\]
\[\sqrt{x} = - 20\]
\[Ответ:корней\ нет.\]
\[7)\sqrt{7x} - 4 = 0\]
\[\sqrt{7x} = 4\]
\[7x = 16\]
\[x = \frac{16}{7}\]
\[Ответ:x = \frac{16}{7}.\]
\[8)\ \sqrt{7x - 4} = 0\]
\[7x - 4 = 0\]
\[x = \frac{4}{7}\ \]
\[Ответ:x = \frac{4}{7}.\]
\[9)\ \sqrt{7x - 4} = 2\]
\[7x - 4 = 4\]
\[7x = 8\]
\[x = \frac{8}{7}\]
\[Ответ:x = \frac{8}{7}.\]
\[10)\ \frac{28}{\sqrt{x}} = 7\]
\[\sqrt{x} = 4\]
\[x = 16\]
\[Ответ:x = 16.\]
\[11)\ \frac{15}{\sqrt{x + 4}} = 3\]
\[\sqrt{x + 4} = 5\]
\[x + 4 = 25\]
\[x = 21\]
\[Ответ:x = 21.\]
\[12)\ \sqrt{4 + \sqrt{3 + x}} = 5\]
\[4 + \sqrt{3 + x} = 25\]
\[\sqrt{3 + x} = 21\]
\[3 + x = 441\]
\[x = 438\]
\[Ответ:x = 438.\]