\( \frac{14a^3b^5}{21a^4b^6} = \frac{14}{21} \cdot \frac{a^3}{a^4} \cdot \frac{b^5}{b^6} \)
\( = \frac{2}{3} \cdot \frac{1}{a} \cdot \frac{1}{b} = \frac{2}{3ab} \)
\( \frac{x^2 + x}{x^2} = \frac{x(x+1)}{x^2} \)
\( = \frac{x+1}{x} \)
Ответ: а) $$\frac{2}{3ab}$$; б) $$\frac{x+1}{x}$$.