Rút gọn:
1. \(\frac{1}{5}\)x2y7. (-10x3yz2).(\(\frac{1}{4}\)x5y2z)
2. -3x4yz. (\(-\frac{1}{6}\)x3yz2).(\(-\frac{5}{2}\)x4y3z)
3. \(-\frac{1}{4}\)x3y4z5. (\(\frac{8}{9}\)x2yz).(\(-\frac{3}{5}\)xyz3)
4. \(\frac{5}{3}\)x4y3z5. (\(-\frac{3}{10}\)xy2z).(\(-\frac{2}{7}\)x5yz)
5. \(-\frac{1}{2}\)x4y7. (\(-\frac{2}{5}\)xyz).(\(\frac{10}{7}\)xz3).(-14y2z3)