Question

13．計(jì)算． 
$\frac{14}{11}$÷21×$\frac{7}{11}$                   
$\frac{3}{4}$×$\frac{5}{8}$÷$\frac{5}{6}$              
$\frac{1}{8}$×14÷$\frac{7}{8}$．

Answer 1

分析 ①$\frac{14}{11}$÷21×$\frac{7}{11}$，把除數(shù)轉(zhuǎn)化為乘它的倒數(shù)，再根據(jù)分?jǐn)?shù)乘法的計(jì)算法則計(jì)算；                  
②$\frac{3}{4}$×$\frac{5}{8}$÷$\frac{5}{6}$，先算乘法，再算除法；           
③$\frac{1}{8}$×14÷$\frac{7}{8}$，先算乘法，再算除法；

解答 解：①$\frac{14}{11}$÷21×$\frac{7}{11}$   
=$\frac{14}{11}×\frac{1}{21}×\frac{7}{11}$
=$\frac{2}{33}×\frac{7}{11}$
=$\frac{14}{363}$；
                
②$\frac{3}{4}$×$\frac{5}{8}$÷$\frac{5}{6}$     
=$\frac{15}{32}×\frac{6}{5}$
=$\frac{9}{16}$；
         
③$\frac{1}{8}$×14÷$\frac{7}{8}$
=$\frac{7}{4}×\frac{8}{7}$
=2．

點(diǎn)評(píng) 此題考查的目的是理解掌握分?jǐn)?shù)四則混合運(yùn)算的順序以及它們的計(jì)算法則，并且能夠正確熟練地進(jìn)行計(jì)算．