能简算的要简算.([3/4]-[3/4]×[2/5])÷[1/5]([2/3]-[1/2]+[1/6])÷[1/24]7

3个回答

  • 解题思路:(1)括号内运用乘法分配律简算,然后再算括号外的;

    (2)括号内进行通分计算,然后再算括号外的,把除法改为乘法计算;

    (3)运用除法的性质简算;

    (4)根据数字特点,把原式变为1.28×2.37-0.28×2.37,运用乘法分配律简算;

    (5)把百分数和分数转化为小数0.65,运用乘法分配律简算.

    (1)([3/4]-[3/4]×[2/5])÷[1/5],

    =[(1-[2/5])×[3/4]]×5,

    =[3/5]×[3/4]×5,

    =[9/4];

    (2)([2/3]-[1/2]+[1/6])÷[1/24],

    =[1/3]×24,

    =8;

    (3)7.28÷0.8÷12.5,

    =7.28÷(0.8×12.5),

    =7.28÷10,

    =0.728;

    (4)1.28×2.37-2.8×0.237,

    =1.28×2.37-0.28×2.37,

    =(1.28-0.28)×2.37,

    =1×2.37,

    =2.37;

    (5)0.65×14+87×65%-[13/20],

    =0.65×14+87×0.65-0.65,

    =0.65×(14+87-1),

    =0.65×100,

    =65.

    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: 考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.