解:1/2=1-(1/2) 1/6=1/(2*3)=(1/2)- (1/3) 1 /12=1/(3*4)=(1/3)- (1/4)
1 /20=1/(4*5)=(1/4)- (1/5) 1 /30=1/(5*6)=(1/5)- (1/6)
所以原式=1-(1/2)+(1/2)- (1/3)+(1/3)- (1/4)+(1/4)- (1/5)+(1/5)- (1/6)
=1-(1/6)
=5/6
(1/2+1/20)+(1/6+1/12)+1/30
不会啊