Question

5．递等式计算
$\frac{4}{9}$×$\frac{9}{14}$$÷\frac{4}{21}$        
$\frac{1}{5}$+$\frac{2}{9}$×$\frac{3}{10}$     
$\frac{1}{3}$×$\frac{3}{4}$÷（$\frac{3}{4}$-$\frac{5}{12}$）        
[1-（$\frac{3}{7}$$+\frac{5}{14}$）]$÷\frac{1}{7}$．

Answer 1

分析 按从左到右运算顺序计算即可．

解答 解：①$\frac{4}{9}×\frac{9}{14}÷\frac{4}{21}$
=$\frac{2}{7}×\frac{21}{4}$
=$\frac{3}{2}$

②$\frac{1}{5}+\frac{2}{9}×\frac{3}{10}$
=$\frac{3}{15}+\frac{1}{15}$
=$\frac{4}{15}$

③$\frac{1}{3}×\frac{3}{4}÷（\frac{3}{4}-\frac{5}{12}）$
=$\frac{1}{4}×3$
=$\frac{3}{4}$

④$[1-（\frac{3}{7}+\frac{5}{14}）]÷\frac{1}{7}$
=$[1-\frac{11}{14}]×7$
=$\frac{3}{14}×7$
=$\frac{3}{2}$

点评 本题主要考查分数四则混合运算的计算顺序．