[tex]\displaystyle\bf\\1\\\\\frac{3}{4} \cdot\Big(-\frac{2}{3} m^{4} n^{4}\Big)=-\frac{1}{2}m^{4} n^{4} \\\\2)\\\\-\frac{1}{2}m^{4} n^{4} \cdot\Big(-\frac{1}{2} m^{1-k} n^{k}\Big)=\frac{1}{4}m^{4+1-k} n^{4+k}=\frac{1}{4}m^{5-k} n^{4+k}\\\\3)\\\\\Big(\frac{1}{4} m^{5-k} n^{4+k}\Big)^{2} =\frac{1}{16} m^{10-2k} n^{8+2k}\\\\4)\\\\\frac{1}{16}m^{10-2k} n^{8+2k}\cdot8m^{k} n^{2-2k} =\frac{1}{2} m^{10-2k+k} n^{8+2k-2k} =\frac{1}{2}m^{10-k} n^{8} \\\\5)[/tex]

[tex]\displaystyle\bf\\\frac{1}{2} \cdot 0,2^{10-8}\cdot 1^{8} =\frac{1}{2}\cdot0,04\cdot 1=0,02\\\\Otvet:0,02[/tex]