Question

16．递等式计算
$\frac{6}{7}$÷$\frac{2}{7}$×$\frac{4}{9}$         
$\frac{1}{3}$÷（$\frac{2}{3}$-$\frac{2}{5}$）×$\frac{3}{5}$         
$\frac{3}{10}$×[$\frac{7}{8}$÷（$\frac{3}{5}$-$\frac{1}{4}$）]．

Answer 1

分析 按从左到右运算顺序计算即可．

解答 解：①$\frac{6}{7}÷\frac{2}{7}×\frac{4}{9}$
=$\frac{6}{7}×\frac{7}{2}×\frac{4}{9}$
=$\frac{4}{3}$

②$\frac{1}{3}÷（\frac{2}{3}-\frac{2}{5}）×\frac{3}{5}$
=$\frac{1}{3}÷\frac{4}{15}×\frac{3}{5}$
=$\frac{1}{3}×\frac{15}{4}×\frac{3}{5}$
=$\frac{3}{4}$

③$\frac{3}{10}×[\frac{7}{8}÷（\frac{3}{5}-\frac{1}{4}）]$
=$\frac{3}{10}×[\frac{7}{8}×\frac{20}{7}]$
=$\frac{3}{10}×\frac{5}{2}$
=$\frac{3}{4}$

点评 本题主要考查分数四则混合运算的计算顺序．