解题思路:(1)(2)按照先算第二级运算,再算第一级运算的顺序解答,
(3)运用乘法交换律和结合律解答,
(4)运用乘法交换律解答,
(5)(6)(7)(8)运用乘法分配律解答.
(1)[4/5+
5
3×
12
25],
=[4/5]+[4/5],
=1[3/5];
(2)10−
2
3×
9
10,
=10-[3/5],
=9[2/5];
(3)[1/7×
1
9×7×9,
=(
1
7×7)×(
1
9×9),
=1×1,
=1;
(4)36×
3
4×
11
36],
=36×[11/36]×[3/4],
=11×[3/4],
=8.[1/4];
(5)[10/21×
2
5+
2
5×
11
21],
=([10/21]+
11
21)×[2/5],
=1×[2/5],
=[2/5];
(6)[9/20×399+
9
20],
=[9/20]×(399+1),
=[9/20×400,
=180;
(7)(
7
36+
5
12−
1
4)×36,
=
7
36]×36+[5/12×36-
1
4×36,
=7+15-9,
=22-9,
=13;
(8)25×
1
24],
=24×[1/24]+1×[1/24],
=1+
1
24,
=1[1/24].
点评:
本题考点: 分数的四则混合运算;运算定律与简便运算.
考点点评: 本题考查知识点:(1)依据四则运算顺序正确进行计算,(2)正确运用简便方法解决问题.