\[\ x > 0:\ \]
\[2x²\sqrt{\frac{49}{x^{2}}} = \frac{2 \cdot 7x²}{|x|} = \frac{14x^{2}}{x} = 14x.\ \]
\[5,2^{2} = 27,04;\]
\[5,3^{2} = 28,09;\]
\[5,2 < \sqrt{28} < 5,3.\]
\[\frac{10}{\sqrt{x} - 2}\]
\[\sqrt{x} - 2 \neq 0\]
\[\sqrt{x} \neq 2\]
\[x \neq 4\]
\[Выражение\ имеет\ смысл\ при\ x > 0\ \ и\ \ \]
\[x \neq 4.\]
\[\frac{1}{6}\sqrt{144} + \frac{1}{3}\sqrt{0,81} = \frac{1}{6} \cdot 12 + \frac{1}{3} \cdot 0,9 =\]
\[= 2 + 0,3 = 2,3\]