五年级分数简便计算:1/(10*12)+1/(12*14)+1/(14*16)+1/(16*18)怎么简便运算啊

问题描述:

五年级分数简便计算:1/(10*12)+1/(12*14)+1/(14*16)+1/(16*18)怎么简便运算啊

1/(10*12)=1/2(1/10-1/12)
1/(10*12)+1/(12*14)+1/(14*16)+1/(16*18)
=1/2(1/10-1/12+1/12-1/14+1/14-1/16+1/16-1/18)
=1/2(1/10-1/18)
=1/45