8.
[tex]N \ poniewaz \ B: \ 20-5 = 15[/tex]
9.
[tex]a) \ 6^{7}\cdot6^{3} =6^{7+3} = 6^{10}\\\\b) \ 5^{8}:5^{2} = 5^{8-2} = 5^{6}\\\\c) \ (\frac{1}{7})^{3}\cdot49^{3} = (\frac{1}{7}\cdot49)^{3} = 7^{3}\\\\d) \ 18^{4}:3^{4} = (18:3)^{4} = 6^{4}\\\\e) \ (4^{3})^{2} = 4^{3\cdot2} = 4^{6}\\\\f) \ ((-2)^{3})^{4} = (-2)^{12} = 2^{12}[/tex]
10.
[tex]a) \ -3^{8}<0\\\\b) \ (-3)^{8} > 0\\\\c) \ -8^{3} < 0\\\\d) \ (-3)^{3} < 0[/tex]
11.
[tex]a) \ 10\cdot(\frac{8}{9}+\frac{9}{8})^{0} = 10\cdot1 = 10\\\\b) \ \frac{2}{3}+(\frac{2}{3})^{2} + \frac{2^{2}}{3}+\frac{2}{3^{2}} = \frac{2}{3}+\frac{4}{9}+\frac{4}{3}+\frac{2}{9} = \frac{6}{3}+\frac{6}{9} = 2+\frac{2}{3} = 2\frac{2}{3}\\\\c) \ (2^{2}+3\cdot2^{2}):2^{4} = (4+3\cdot4):16 = (4+12):16 = 16:16 = 1\\\\d) \ (2,5)^{2}-2\cdot(\frac{3}{2})^{2}+(-3)^{2} =6,25-2\cdot(1,5)^{2}+9 = 15,25-2\cdot2,25 = \\=15,25 - 4,5 = 10,75[/tex]
