Сократите дробь: a) $$\frac{14a^4b}{49a^3b^2}$$ b) $$\frac{3x}{x^2+4x}$$ v) $$\frac{y^2-z^2}{2y+2z}$$

a) $$\frac{14a^4b}{49a^3b^2} = \frac{2a}{7b}$$ b) $$\frac{3x}{x^2+4x} = \frac{3x}{x(x+4)} = \frac{3}{x+4}$$ v) $$\frac{y^2-z^2}{2y+2z} = \frac{(y-z)(y+z)}{2(y+z)} = \frac{y-z}{2}$$