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.