Решите уравнение: (x^2+4x)/15=(5x+56)*15.

\[\frac{x^{2} + 4x}{15} = \frac{5x + 56}{15}\ \ | \cdot 15\]

\[x^{2} + 4x = 5x + 56\]

\[x^{2} - x - 56 = 0\]

\[x_{1} + x_{2} = 1;\ \ x_{1} \cdot x_{2} = 56\]

\[x_{1} = - 7;\ \ \ x_{2} = 8.\]

\[Ответ:x = - 7;\ \ x = 8.\]