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1. $(-3)÷ \left(\frac{1}{3}\right)= $
答案
-9
解析
$(-3)÷\left(\frac{1}{3}\right)=(-3)×3=-9$
2. $(-56)× \frac{1}{8}= $
答案
-7
3. $\frac{1}{78}÷ \left(-\frac{1}{13}\right)= $
答案
$-\frac{1}{6}$
解析
$\frac{1}{78}÷\left(-\frac{1}{13}\right)=\frac{1}{78}×(-13)=-\frac{13}{78}=-\frac{1}{6}$
4. $\left(-2\frac{3}{5}\right)× \frac{10}{13}= $
答案
-2
解析
$-2\frac{3}{5} = -\frac{13}{5}$，$-\frac{13}{5}×\frac{10}{13} = -2$
5. $( )÷ (-27)= 5$
答案
-135
解析
设括号里的数为$x$，则$x÷(-27)=5$，$x = 5×(-27)=-135$
-135
-135
6. $126÷ ( )= -21$
答案
-6
解析
设括号内的数为$x$，则$126÷ x=-21$，解得$x=126÷(-21)=-6$。
-6
-6
7. $( )× (-12)= -144$
答案
12
8. $(-13)× ( )= 52$
答案
-4
解析
设括号内的数为$x$，则$(-13)×x = 52$，解得$x = 52÷(-13) = -4$
-4
-4
9. $(-81)÷ \frac{9}{5}× \frac{5}{9}$
答案
-25
解析
$(-81)÷\frac{9}{5}×\frac{5}{9}$
$=(-81)×\frac{5}{9}×\frac{5}{9}$
$=-45×\frac{5}{9}$
$=-25$
$=(-81)×\frac{5}{9}×\frac{5}{9}$
$=-45×\frac{5}{9}$
$=-25$
10. $(-0.01)× (-0.1)÷ 0.001$
答案
1
解析
$(-0.01)×(-0.1) = 0.001$
$0.001÷0.001 = 1$
1
$0.001÷0.001 = 1$
1
11. $208÷ \left(-1-\frac{4}{5}\right)× 0$
答案
0
解析
$208÷\left(-1-\frac{4}{5}\right)×0$
$=208÷\left(-\frac{9}{5}\right)×0$
$=0$
$=208÷\left(-\frac{9}{5}\right)×0$
$=0$
12. $\left(0.625-\frac{1}{6}+\frac{7}{12}\right)÷ \left(-\frac{1}{24}\right)$
答案
-25
解析
$\left(0.625 - \frac{1}{6} + \frac{7}{12}\right) ÷ \left(-\frac{1}{24}\right)$
$=\left(\frac{5}{8} - \frac{1}{6} + \frac{7}{12}\right) × (-24)$
$=\frac{5}{8} × (-24) - \frac{1}{6} × (-24) + \frac{7}{12} × (-24)$
$=-15 + 4 - 14$
$=-25$
$=\left(\frac{5}{8} - \frac{1}{6} + \frac{7}{12}\right) × (-24)$
$=\frac{5}{8} × (-24) - \frac{1}{6} × (-24) + \frac{7}{12} × (-24)$
$=-15 + 4 - 14$
$=-25$
13. $36.5× (-1.28)+(-63.5)× 1.28$
答案
-128
解析
$36.5×(-1.28)+(-63.5)×1.28$
$=-36.5×1.28-63.5×1.28$
$=1.28×(-36.5-63.5)$
$=1.28×(-100)$
$=-128$
$=-36.5×1.28-63.5×1.28$
$=1.28×(-36.5-63.5)$
$=1.28×(-100)$
$=-128$
14. $\left(-2\frac{13}{16}\right)÷ \left(\frac{3}{4}× \frac{9}{8}\right)$
答案
$-\frac{10}{3}$
解析
$(-2\frac{13}{16})÷(\frac{3}{4}×\frac{9}{8})$
$=(-\frac{45}{16})÷\frac{27}{32}$
$=(-\frac{45}{16})×\frac{32}{27}$
$=-\frac{45×32}{16×27}$
$=-\frac{1440}{432}$
$=-\frac{10}{3}$
$=(-\frac{45}{16})÷\frac{27}{32}$
$=(-\frac{45}{16})×\frac{32}{27}$
$=-\frac{45×32}{16×27}$
$=-\frac{1440}{432}$
$=-\frac{10}{3}$
15. $\left(-2\frac{2}{5}\right)× \left[\left(+\frac{5}{6}\right)÷ \left(-\frac{2}{3}\right)\right]$
答案
3
解析
$\begin{aligned}\left(-2\frac{2}{5}\right)× \left[\left(+\frac{5}{6}\right)÷ \left(-\frac{2}{3}\right)\right]&=-\frac{12}{5}×\left[\frac{5}{6}×\left(-\frac{3}{2}\right)\right]\\&=-\frac{12}{5}×\left(-\frac{5}{4}\right)\\&=3\end{aligned}$
16. $7\frac{1}{3}× \left(-\frac{1}{12}\right)÷ \left(\frac{1}{9}÷ \frac{3}{14}\right)$
答案
$-\frac{33}{28}$
解析
$7\frac{1}{3}×\left(-\frac{1}{12}\right)÷\left(\frac{1}{9}÷\frac{3}{14}\right)$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)÷\left(\frac{1}{9}×\frac{14}{3}\right)$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)÷\frac{14}{27}$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)×\frac{27}{14}$
$=-\frac{22×1×27}{3×12×14}$
$=-\frac{22×9}{12×14}$
$=-\frac{198}{168}$
$=-\frac{33}{28}$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)÷\left(\frac{1}{9}×\frac{14}{3}\right)$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)÷\frac{14}{27}$
$=\frac{22}{3}×\left(-\frac{1}{12}\right)×\frac{27}{14}$
$=-\frac{22×1×27}{3×12×14}$
$=-\frac{22×9}{12×14}$
$=-\frac{198}{168}$
$=-\frac{33}{28}$
