计算:①[3/4]+[1/6]-[3/8]= ②3.2-0.85-1[4/5]= ③3.2×[5/8]-[2/3]÷2=

1个回答

  • 解题思路:①②③⑦⑧根据四则混合运算法运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;

    ④可根据乘法结合律计算;

    ⑤⑥可根据乘法分配律计算;

    ①[3/4]+[1/6]-[3/8]

    =[11/12]-[3/8],

    =[13/24];

    ②3.2-0.85-1[4/5]

    =2.35-1.8,

    =0.55;

    ③3.2×[5/8]-[2/3]÷2

    =2-[1/3],

    =1[2/3];

    ④1.725×4×0.5

    =1.725×(4×0.5),

    =1.725×2,

    =3.5;

    ⑤([7/8]+[13/16])÷[13/16]

    =[7/8]×[16/13]+[13/16]×[16/13],

    =[14/13]+1,

    =2[1/13];

    ⑥1.8×0.72+1.28×1.8

    =1.8×(0.72+1.28),

    =1.8×2,

    =3.6;

    ⑦2÷([1/2]-[1/3])

    =2÷[1/6],

    =12;

    ⑧57.6÷[(1.25+25%)×0.32]

    =57.6÷[1.5×0.32],

    =57.6÷0.48,

    =120.

    点评:

    本题考点: 整数、分数、小数、百分数四则混合运算;运算定律与简便运算.

    考点点评: 当算式中同时含有中括号与小括号时,要注意先算小括号里面的,再算中括号里面的.