1/(4)=1/4
1/(4×7)=(1/3)×[1/4-1/7]
1/(7×10)=(1/3)×[1/7-1/10]
1/(10×13)=(1/3)×[1/10-1/13]
1/(13×14)=(1/3)×[1/13-1/16]
则原式=(1/4)+(1/3)×[(1/4)-(1/7)+(1/7)-(1/10)+(1/10)-(1/13)+(1/13)-(1/16)]
=(1/4)+(1/3)×[(1/4)-(1/16)]
=(1/4)+(1/3)×(3/16)
=5/16
1/(4)=1/4
1/(4×7)=(1/3)×[1/4-1/7]
1/(7×10)=(1/3)×[1/7-1/10]
1/(10×13)=(1/3)×[1/10-1/13]
1/(13×14)=(1/3)×[1/13-1/16]
则原式=(1/4)+(1/3)×[(1/4)-(1/7)+(1/7)-(1/10)+(1/10)-(1/13)+(1/13)-(1/16)]
=(1/4)+(1/3)×[(1/4)-(1/16)]
=(1/4)+(1/3)×(3/16)
=5/16