I'm not 100% sure of these answers but this is what I got:
6. [tex]\frac{1}{t^{2}}[/tex] I subtracted [tex]t^{4-6} = t^{-2} = \frac{1}{t^{2}}[/tex]
7. (-5a³)² = [tex]25a^{6}[/tex] You square the -5 and a³
8. [tex](\frac{b^{4}}{3} )^{-6} = \frac{1}{(\frac{b^{4}}{3} )^{6}} = \frac{1}{\frac{b^{24}}{3^{6}} } = \frac{1}{\frac{b^{24}}{729} } \frac{\frac{729}{b^{4}} }{\frac{729}{b^{4}} } =\frac{729}{b^{4}}[/tex]
9. 8.9 x [tex]10^{5}[/tex]
10. 8.9816 x [tex]10^{-5}[/tex]
11. 3180
12. 0.000866
13. [tex]\frac{900000}{0.0003} = 3000000000[/tex]
3.0 x [tex]10^{9}[/tex]
14. 8x² + 2x - 8 for x = 2
8(2)² + 2(2) - 8 = 8(4) + 4 - 8 = 32 - 4 = 28
