题目内容
4.| 脱式计算,能简算的要简算. $\frac{7}{9}$÷$\frac{11}{5}$+$\frac{2}{9}$×$\frac{5}{11}$ | 1.25×32×0.25 | 2.3+3.91÷(22-19.7) |
| $\frac{2}{3}$+( $\frac{5}{6}$-0.75 )÷$\frac{3}{8}$ | 6÷$\frac{3}{5}$-$\frac{3}{5}$÷6 | 43×$\frac{1}{4}$+25%×58-0.25. |
分析 (1)、(6)利用乘法的分配律进行计算;
(2)把32改写成4×8后再利用乘法结合律进行计算;
(3)先算小括号内面的减法,再算小括号外的除法,最后算加法;
(4)先算小括号内面的减法,再算小括号外的除法,最后算加法;
(5)先算第二级运算,再算第一级运算.
解答 解:(1)$\frac{7}{9}$÷$\frac{11}{5}$+$\frac{2}{9}$×$\frac{5}{11}$
=$\frac{7}{9}$×$\frac{5}{11}$+$\frac{2}{9}$×$\frac{5}{11}$
=$\frac{5}{11}$×($\frac{7}{9}$+$\frac{2}{9}$)
=$\frac{5}{11}$×1
=$\frac{5}{11}$
(2)1.25×32×0.25
=1.25×(4×8)×0.25
=(1.25×8)×(4×0.25)
=10×1
=10
(3)2.3+3.91÷(22-19.7)
=2.3+3.91÷2.3
=2.3+1.7
=4
(4)$\frac{2}{3}$+( $\frac{5}{6}$-0.75 )÷$\frac{3}{8}$
=$\frac{2}{3}$$+\frac{1}{12}$$÷\frac{3}{8}$
=$\frac{2}{3}$+$\frac{2}{9}$
=$\frac{8}{9}$
(5)6÷$\frac{3}{5}$-$\frac{3}{5}$÷6
=6×$\frac{5}{3}$-$\frac{3}{5}$×$\frac{1}{6}$
=10-$\frac{1}{10}$
=9$\frac{9}{10}$
(6)43×$\frac{1}{4}$+25%×58-0.25
=43×$\frac{1}{4}$+$\frac{1}{4}$×58-$\frac{1}{4}$×1
=$\frac{1}{4}$×(43+58-1)
=$\frac{1}{4}$×100
=25
点评 考查学生对于四则运算法则及运算定律的掌握情况.