[tex]8.\\\\1)\\m^7=-1\\m=\sqrt[7]{-1}=-1\\\\n^3=\frac{1}{8}\\\\n=\sqrt[3]{\frac{1}{8}}=\frac{1}{2}\\\\2)\\8m^3n^2=8\cdot (-1)^3\cdot(\frac{1}{2})^2=8\cdot (-1)\cdot\frac{1}{4}=-2[/tex]

[tex]9.\\\\-2,7b-3(a-b)+1,7b=-2,7b-3a+3b+1,7b=-3a+2b\\\\-3\cdot 8+2\cdot (-3,5)=-24-7=-31[/tex]

[tex]10.\\\\(-\frac{1}{4}x^4y^3)^2\cdot(2xy^2)^3-0,5y^2(0,1x^{11}y^{10}=\\\\\frac{1}{16}x^8y^6\cdot 8x^3y^6-0,5y^{12}x^{11}=\\\\\frac{1}{2}x^{11}y^{12}-0,5y^{12}x^{11}=0[/tex]