Question

5/6-3/7+7/12+2/21怎么算？

Answer 1

解：5/6－3/7+7/12+2/21等于( 13/12 )
∵已知需求出5/6－3/7+7/12+2/21等于多少
∴5/6－3/7 + 7/12 + 2/21
= （5×42）/（6×42）- （3×36）/（7×36）+（7×21）/（12×21）+（2×12）/(21×12)
= 210/252 - 108/252 + 147/252 + 24/252
= 102/252 + 147/252 + 24/252
= 249/252 + 24/252
= 273/252
= （13×21）/（12×21）
= 13/12
答：5/6－3/7+7/12+2/21等于13/12

Answer 2

5/6-3/7+7/12+2/21
=(5/6+7/12)+(2/21-3/7)
=(10/12+7/12)+(2/21-9/21)
=17/12-7/21
=17/12-1/3
=17/12-4/12
=13/12