1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算

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1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算

1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算
1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算

1/1*3+1/3*5+1/5*7+.+1/49*51怎么计算
1/1*3+1/3*5+1/5*7+.+1/49*51
=(1-1/3)*1/2+(1/3-1/5)*1/2+(1/5-1/7)*1/2+...+(1/49-1/51)*1/2
=(1-1/51)*1/2
=50/51*1/2
=25/51

1/1*3=1/2(1-1/3)
1/3*5=1/2(1/3-1/5)
1/5*7=1/2(1/5-1/7)
.....
1/49*51=1/2(1/49-1/51)
1/1*3+1/3*5+1/5*7+。。。。。。。+1/49*51
=1/2(1-1/3+1/3-1/5+1/5-1/7.....1/49-1/51)
=1/2(1-1/51)
=1/2*50/51
=25/51