Đáp án:
8. $\frac{-7}{6}$
9. $-3$
10. $-57$
11. $-4$
12. $\frac{-41}{90}$
Giải thích các bước giải:
8. $(\frac{1}{3})^{50}×(-9)^{25} - \frac{2}{3} : 4$
= $(\frac{1}{3})^{50}×(-3^{2})^{25} - \frac{2}{3}×\frac{1}{4}$
= $-\frac{1}{3^{50}}×3^{50} - \frac{1}{6}$
= $-1 - \frac{1}{6}$
= $\frac{-7}{6}$
9. $\frac{3}{5} : ( \frac{-1}{15} - \frac{1}{6} ) + \frac{3}{5} : ( \frac{-1}{3} - 1\frac{1}{15} )$
= $\frac{3}{5} : ( \frac{-2}{30} - \frac{5}{30} ) + \frac{3}{5} : ( \frac{-5}{15} - \frac{16}{15} )$
= $\frac{3}{5} : \frac{-7}{30} + \frac{3}{5} : \frac{-7}{5}$
= $\frac{3}{5}×\frac{-30}{7} + \frac{3}{5}×\frac{-5}{7}$
= $\frac{3}{5}× ( \frac{-30}{7} + \frac{-5}{7} )$
= $\frac{3}{5}×\frac{-35}{7}$
= $\frac{3}{5}×(-5)$
= $-3$
10. $(-6,5)×5,7 + 5,7×(-3,5)$
= $5,7×( -6,5 - 3,5 )$
= $5,7×(-10)$
= $-57$
11. $\frac{2^{4}×2^{6}}{(2^{5})^{2}} - \frac{2^{5}×15^{3}}{6^{3}×10^{2}}$
= $\frac{2^{10}}{2^{10}} - \frac{2^{5}×5^{3}×3^{3}}{3^{3}×2^{3}×5^{2}×2^{2}}$
= $1 - \frac{2^{5}×5^{3}×3^{3}}{3^{3}×2^{5}×5^{2}}$
= $1 - 5$
= $-4$
12. $- ( \frac{3}{54} + \frac{3}{4} ) - ( \frac{-3}{4} + \frac{2}{5} )$
= $- \frac{1}{18} - \frac{3}{4} + \frac{3}{4} - \frac{2}{5}$
= $\frac{-1}{18} - \frac{2}{5}$
= $\frac{-5-2×18}{90}$
= $\frac{-41}{90}$
