Question

8．用遞等式計(jì)算
$\frac{4}{9}$×$\frac{1}{5}$÷$\frac{4}{5}$           
$\frac{1}{2}$×$\frac{2}{5}$+$\frac{9}{10}$÷$\frac{9}{20}$
[1-（$\frac{1}{4}$+$\frac{3}{8}$）]÷$\frac{1}{4}$．

Answer 1

分析 按運(yùn)算順序計(jì)算即可．

解答 解：①$\frac{4}{9}×\frac{1}{5}÷\frac{4}{5}$
=$\frac{4}{9}×\frac{1}{5}×\frac{5}{4}$
=$\frac{1}{9}$

②$\frac{1}{2}×\frac{2}{5}+\frac{9}{10}÷\frac{9}{20}$
=$\frac{1}{5}+\frac{9}{10}×\frac{20}{9}$
=$\frac{1}{5}+2$
=$2\frac{1}{5}$

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

點(diǎn)評(píng) 本題主要考查分?jǐn)?shù)四則混合運(yùn)算的計(jì)算順序．