也就是1/4+(3/7-3/14)对吧.
1/4+(3/7-3/14)
=1/4+(6/14-3/14)
=1/4+3/14
=13/28
这是通分计算,把3/7分子分母同时扩大了2倍.
望大家采纳!!
1/4+3/7-3/14
=1/4+6/14-3/14
=1/4+3/14
=7/28+6/28
=13/28
1/4+3/7-3/14=1/4+6/14-3/14=1/4+3/14=7/28+2/28=9/28
1/4+3/7-3/14
= 1/4+(3/7-3/14)
= 1/4+(6/14-3/14)
= 1/4+3/14
= 14/56+12/56
= 13/28
运用加法交换律