怎样简便就怎样算 ([1/4+38])÷(1-[2/7])= 6.8×2.5+2.5×3.2= 36÷[([5/6×

1个回答

  • 解题思路:(1)两个括号同时计算,然后算除法;

    (2)运用乘法分配律简算:

    (3)先去小括号,中括号内约分计算,最后算括号外的;

    (4)把除法转化为乘法,发现减号前后算式相等,故结果为0;

    (5)把除法转化为乘法,运用乘法分配律简算;

    (6)把1[2/5]化为小数,运用乘法分配律简算.

    (1)([1/4]+[3/8])÷(1-[2/7]),

    =[5/8]÷[5/7],

    =[5/8]×[7/5],

    =[7/8];

    (2)6.8×2.5+2.5×3.2,

    =(6.8+3.2)×2.5,

    =10×2.5,

    =25;

    (3)36÷[([5/6×

    1

    3])×3],

    =36÷[[5/6×

    1

    3]×3],

    =36÷[5/6],

    =36×[6/5],

    =43.2;

    (4)[2/3]÷[5/4]-[2/3]×[4/5],

    =[2/3]×[4/5]-[2/3]×[4/5],

    =0;

    (5)[7/8]÷5+[7/8]÷7,

    =[7/8]×[1/5]+[7/8]×[1/7],

    =[7/8]×([1/5]+

    点评:

    本题考点: 分数的四则混合运算;运算定律与简便运算;小数四则混合运算.

    考点点评: 完成本题要注意分析式中数据,运用合适的简便方法计算.