Решите уравнение: 7x^3-28x=0.

\[7x³ - 28x = 0\]

\[7x\left( x^{2} - 4 \right) = 0\]

\[7x(x - 2)(x + 2) = 0\]

\[x = 0,\ \ x = 2,\ \ x = - 2\]

\[Ответ:x = 0;\ x = \pm 2.\]