Question

16．計(jì)算下面各題，請(qǐng)寫(xiě)出主要計(jì)算過(guò)程．

①$\frac{5}{7}$×$\frac{5}{8}$×$\frac{7}{5}$	②60×（$\frac{5}{12}$+$\frac{1}{4}$-$\frac{2}{15}$）	③3÷$\frac{2}{5}$÷$\frac{2}{5}$
④$\frac{1}{3}$×$\frac{5}{6}$÷$\frac{1}{3}$×$\frac{5}{6}$	⑤$\frac{7}{9}$÷$\frac{11}{5}$+$\frac{2}{9}$×$\frac{5}{11}$	⑥$\frac{2}{13}$÷$\frac{15}{26}$×$\frac{5}{8}$

Answer 1

分析 ①根據(jù)乘法交換律進(jìn)行簡(jiǎn)算；
②、⑤根據(jù)乘法分配律進(jìn)行簡(jiǎn)算；
③、④、⑥按照從左向右的順序進(jìn)行計(jì)算．

解答 解：①$\frac{5}{7}$×$\frac{5}{8}$×$\frac{7}{5}$
=$\frac{5}{7}$×$\frac{7}{5}$×$\frac{5}{8}$
=1×$\frac{5}{8}$
=$\frac{5}{8}$；

②60×（$\frac{5}{12}$+$\frac{1}{4}$-$\frac{2}{15}$）
=60×$\frac{5}{12}$+60×$\frac{1}{4}$-60×$\frac{2}{15}$
=25+15-8
=40-8
=32；

③3÷$\frac{2}{5}$÷$\frac{2}{5}$
=$\frac{15}{2}$÷$\frac{2}{5}$
=$\frac{75}{4}$；

④$\frac{1}{3}$×$\frac{5}{6}$÷$\frac{1}{3}$×$\frac{5}{6}$
=$\frac{5}{18}$÷$\frac{1}{3}$×$\frac{5}{6}$
=$\frac{5}{6}$×$\frac{5}{6}$
=$\frac{25}{36}$；

⑤$\frac{7}{9}$÷$\frac{11}{5}$+$\frac{2}{9}$×$\frac{5}{11}$
=$\frac{7}{9}$×$\frac{5}{11}$+$\frac{2}{9}$×$\frac{5}{11}$
=（$\frac{7}{9}$+$\frac{2}{9}$）×$\frac{5}{11}$
=1×$\frac{5}{11}$
=$\frac{5}{11}$；

⑥$\frac{2}{13}$÷$\frac{15}{26}$×$\frac{5}{8}$
=$\frac{4}{15}$×$\frac{5}{8}$
=$\frac{1}{6}$．

點(diǎn)評(píng) 考查了運(yùn)算定律與簡(jiǎn)便運(yùn)算，四則混合運(yùn)算．注意運(yùn)算順序和運(yùn)算法則，靈活運(yùn)用所學(xué)的運(yùn)算定律簡(jiǎn)便計(jì)算．