5) -14x⁷yz² ⋅ 1\frac{2}{7}x²y⁹z⁵;

5) $$-14x^7yz^2 \cdot 1\frac{2}{7}x^2y^9z^5 = -14x^7yz^2 \cdot \frac{9}{7}x^2y^9z^5 = -14 \cdot \frac{9}{7} \cdot x^7 \cdot x^2 \cdot y \cdot y^9 \cdot z^2 \cdot z^5 = -18x^{7+2}y^{1+9}z^{2+5} = -18x^9y^{10}z^7$$.

Ответ: $$-18x^9y^{10}z^7$$