\[\boxed{\text{442\ (442).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[A \neq \varnothing;тогда\ \text{A\ }и\ \varnothing - два\ разных\ \]
\[подмножества\ множества\ A:\]
\[A \subset A;\ \ \varnothing \subset A.\ \]
\[\boxed{\text{442.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ A = \left\{ 4;6;8;9 \right\}.\]
\[2)\ A = \left\{ \frac{5}{1};\frac{5}{2};\frac{5}{3};\frac{5}{4};\frac{5}{5} \right\}.\]
\[3)\ x^{3} - 16x = 0\]
\[x\left( x^{2} - 16 \right) = 0\]
\[x(x - 4)(x + 4) = 0\]
\[x = 0;\ \ x = \pm 4.\]
\[A = \left\{ - 4;0;4 \right\}.\]
\[4)\ \frac{x^{2} - 7x}{x - 7} = 0\]
\[\frac{x(x - 7)}{x - 7} = 0;\ \ x \neq 7\]
\[x = 0.\]
\[A = \left\{ 0 \right\}.\]