Сократите дробь 14a^4b/49a^3b^2.

\[\frac{14a^{4}b}{49a^{3}b^{2}} = \frac{2a}{7b}\]

\[\frac{3x}{x^{2} + 4x} = \frac{3x}{x(x + 4)} = \frac{3}{x + 4}\]