1/(10*11) + 1/(11*12) + .......1/(99*100)= ???
帮个忙,还有个题。1/1*3+1/3*5+1/5*7+......+1/97*99 = ???
楼上答案是对的
1/1*3+1/3*5+1/5*7+......+1/97*99 = ???
1/1*3+1/3*5+1/5*7+......+1/97*99 =1/2x(1-1/3+1/3-1/5+1/5-1/7+...+1/97-1/99)=1/2x(1-1/99)=1/2x98/99=49/99