4) 56x5y14 · 2/7 x2y;

4) $$56x^5y^{14} \cdot \frac{2}{7}x^2y = (56 \cdot \frac{2}{7}) \cdot (x^5 \cdot x^2) \cdot (y^{14} \cdot y) = \frac{56 \cdot 2}{7} \cdot x^{5+2} \cdot y^{14+1} = \frac{8 \cdot 7 \cdot 2}{7}x^7y^{15} = 16x^7y^{15}$$.

Ответ: $$16x^7y^{15}$$