下面各题,怎样算简便就怎样算.(1)[4/5+53×1225] (2)10−23×910 (3)[1/7×19×7×9

1个回答

  • 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

    12

    25],

    =[4/5]+[4/5],

    =1[3/5];

    (2)10−

    2

    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

    11

    36],

    =36×[11/36]×[3/4],

    =11×[3/4],

    =8.[1/4];

    (5)[10/21×

    2

    5+

    2

    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.