(1/4+1/6-1/3)÷1/21
=(3/12+2/12-4/12)x12
=1/12x12
=1
这个题因为有括号所以先计算括号,而括号里面是三个分数,这三个分数的分母不能同时整除21,所以正常通分计算即可。
(1/4+1/6-1/3)÷1/21=(3+2-4)/12÷1/21=1/12×21=7/4
解=(1/4+1/6−1/3)÷1/21
=(3/12+2/12−4/12)÷1/21
=1/12÷1/21
=1/12×21
=21/12
=7/4
(1/4 + 1/6 -⅓)÷1/12
=(1/4 + 1/6 -⅓)x12
=3+2-4
=1
根据题目的简便计算,可以这样计算。
(1/4+1/6-1/3)÷1/21
=(1/4-1/6)×21
=(3/12-2/12)×21
=21/12
=7/4