二十九分之十三×十一+二十九分之十八×十三
=13/29×11+18/29×13
=13/29×11+13/29×18
=13/29×(11+18)
=13/29×29
=13那么 5/13×7+6/13×5 怎么简便？5/13×7+6/13×5 =5/13×7+5/13×6=5/13×（7+6）=5/13×13=5（1+1/2+1/3+1/4）×（1/2+1/3+1/4+1/5）-（1+1/2+1/3+1/4+1/5）×（1/2+1/3+1/4）(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)×(1/2+1/3+1/4)=(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4)×(1/2+1/3+1/4)-1/5×(1/2+1/3+1/4)=(1+1/2+1/3+1/4)×[(1/2+1/3+1/4+1/5)-(1/2+1/3+1/4)]-1/5×(1/2+1/3+1/4)=(1+1/2+1/3+1/4)×[1/2+1/3+1/4+1/5-1/2-1/3-1/4]-1/5×(1/2+1/3+1/4)=(1+1/2+1/3+1/4)×1/5-1/5×(1/2+1/3+1/4)=1/5×[(1+1/2+1/3+1/4)-(1/2+1/3+1/4)]=1/5×(1+1/2+1/3+1/4-1/2-1/3-1/4)=1/5×1=1/52007×（1-1/2）×（1-1/3）×（1-1/4）×...×（1-1/2006）×（1-1/2007）2007×（1-1/2）×（1-1/3）×（1-1/4）×...×（1-1/2006）×（1-1/2007）=2007×1/2×2/3×3/4×……×2005/2006×2006/2007【约分】=2007/2007=1望采纳O(∩_∩)O~