Question

11．脫式計算，能簡算要簡算．
①9×$\frac{2}{3}$+6÷$\frac{2}{3}$       
②$\frac{19}{12}$×$\frac{3}{14}$-$\frac{3}{14}$        
③（ $\frac{4}{9}$+$\frac{5}{6}$-$\frac{1}{3}$）÷$\frac{1}{18}$
④$\frac{5}{8}$×$\frac{1}{9}$+$\frac{1}{8}$÷9+$\frac{1}{4}$×$\frac{1}{9}$           
⑤（ $\frac{1}{10}$+$\frac{3}{5}$+$\frac{8}{15}$）÷$\frac{1}{5}$．

Answer 1

分析 ①先算乘除法，再算加法；
②根據(jù)乘法分配律計算；     
③④⑤將除法變?yōu)槌朔ǎ�再根�?jù)乘法分配律計算．

解答 解：①9×$\frac{2}{3}$+6÷$\frac{2}{3}$    
=6+9
=15   

②$\frac{19}{12}$×$\frac{3}{14}$-$\frac{3}{14}$      
=（$\frac{19}{12}$-1）×$\frac{3}{14}$
=$\frac{7}{12}$×$\frac{3}{14}$      
=$\frac{1}{8}$

③（$\frac{4}{9}$+$\frac{5}{6}$-$\frac{1}{3}$）÷$\frac{1}{18}$
=（$\frac{4}{9}$+$\frac{5}{6}$-$\frac{1}{3}$）×18
=$\frac{4}{9}$×18+$\frac{5}{6}$×18-$\frac{1}{3}$×18
=8+15-6
=17

④$\frac{5}{8}$×$\frac{1}{9}$+$\frac{1}{8}$÷9+$\frac{1}{4}$×$\frac{1}{9}$    
=$\frac{5}{8}$×$\frac{1}{9}$+$\frac{1}{8}$×$\frac{1}{9}$+$\frac{1}{4}$×$\frac{1}{9}$    
=（$\frac{5}{8}$+$\frac{1}{8}$+$\frac{1}{4}$）×$\frac{1}{9}$
=1×$\frac{1}{9}$
=$\frac{1}{9}$  
     
⑤（$\frac{1}{10}$+$\frac{3}{5}$+$\frac{8}{15}$）÷$\frac{1}{5}$
=（$\frac{1}{10}$+$\frac{3}{5}$+$\frac{8}{15}$）×5
=$\frac{1}{10}$×5+$\frac{3}{5}$×5+$\frac{8}{15}$×5
=$\frac{1}{2}$+3+2$\frac{2}{3}$
=6$\frac{1}{6}$．

點評 考查了運算定律與簡便運算，四則混合運算．注意運算順序和運算法則，靈活運用所學的運算定律簡便計算．