1/1*3=1/2(1-1/3) 1/3*5=1/2(1/3-1/5)
1/7*9=1/2(1/5-1/7)
1/1*3+1/3*5+1/5*7+1/7*9+.+1/49*51
=1/2(1-1/3+1/3-1/5+.-1/51)
=1/2(1-1/51)
=25/51谢谢!0^-^0……以后有这类问题可以直接找我o(^-^)o嗯,谢谢!吧我的设成满意吧