Question

15．计算下面各题，能简算的要简算．

7-$\frac{1}{6}$×$\frac{3}{4}$-$\frac{7}{8}$	$\frac{5}{8}$÷[$\frac{13}{12}$-（$\frac{1}{12}$+$\frac{1}{4}$）]	$\frac{17}{12}$×$\frac{1}{5}$-$\frac{5}{12}$÷5
0.28×99+28%	9.6-11÷7+$\frac{4}{7}$	12×[12×（$\frac{11}{6}$-$\frac{2}{3}$）×3]

Answer 1

分析 ①②⑤⑥按照四则混合运算的顺序的计算方法进行计算，运用分数作为计算的结果，要化成最简分数．
③④运用乘法的分配律进行计算即可．

解答 解：①7-$\frac{1}{6}$×$\frac{3}{4}$-$\frac{7}{8}$
=7-$\frac{4}{8}-\frac{7}{8}$
=7-$\frac{11}{8}$
=5$\frac{5}{8}$

②$\frac{5}{8}$÷[$\frac{13}{12}$-（$\frac{1}{12}$+$\frac{1}{4}$）]
=$\frac{5}{8}$÷[$\frac{13}{12}-$$\frac{1}{12}$$-\frac{1}{4}$]
=$\frac{5}{8}$÷[1$-\frac{1}{4}$]
=$\frac{5}{8}$×$\frac{4}{3}$
=$\frac{5}{6}$

③$\frac{17}{12}$×$\frac{1}{5}$-$\frac{5}{12}$÷5
=$\frac{17}{12}$×$\frac{1}{5}$-$\frac{5}{12}$×$\frac{1}{5}$
=（$\frac{17}{12}$-$\frac{5}{12}$）×$\frac{1}{5}$
=$\frac{1}{5}$


④0.28×99+28%  
=0.28×99+0.28
=0.28×（99+1）
=0.28×100
=28

⑤9.6-11÷7+$\frac{4}{7}$  
=9.6-$\frac{11}{7}$$+\frac{4}{7}$
=9.6-1
=8.6

⑥12×[12×（$\frac{11}{6}$-$\frac{2}{3}$）×3]
=12×[12×$\frac{7}{6}$×3]
=12×14×3
=504

点评 本题考查了学生通过约分对分数四则混合运题目进行简算的能力．