
2个回答
展开全部
1/4+1/12+1/24+1/40+......+1/19800
=(1/2+1/6+1/12+1/20+......+1/9900)/2
=(1/1*2+1/2*3+1/3*4+1/4*5+......+1/99*100)/2
=(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+......+1/99-1/100)/2
=(1-1/100)/2
=(99/100)/2
=99/200
祝你成功!
=(1/2+1/6+1/12+1/20+......+1/9900)/2
=(1/1*2+1/2*3+1/3*4+1/4*5+......+1/99*100)/2
=(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+......+1/99-1/100)/2
=(1-1/100)/2
=(99/100)/2
=99/200
祝你成功!
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