1/1*5+1/3*7+1/5*9+.+1/(2n-1)(2n+3)
=【（1-1/5+1/3-1/7+1/5-1/9+.+1/(2n-1)-1/(2n+3) 】÷4
=【1+1/3-1/（2n+1)-1/(2n+3)】÷4
=1/3-（n+1)/[(2n+1)(2n+3)]
1/1*5+1/3*7+1/5*9+.+1/(2n-1)(2n+3)
2个回答
相关问题
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1+3+5+7+9+.+(2n-1)+(2n+1)+(2n+3)=
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求和：Sn=(1/3*5)+(1/5*7)+(1/7*9)+...+[1/(2n+1)(2n+3)]
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1+3+5+7+9+.+(2n-1)+(2n+1)=
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1+2+3+4+5+6+7+8+9+…+n=n(n+1)/2 1+3+5+7+9+11+13+15+…+(2n-1)=n
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数列求和Sn=1/1*3+4/3*5+9/5*7+……n^2/(2n-1)(2n+1)
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1/1*3+1/3*5+1/5*7+.+1/（2n-1）(2n+1)=n/(2n+1)
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1/1*3+1/5*7+ 1/9*11+.1/(2n-1)(2n+1)
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1+3+5+7+9+.+（2n-1）=
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1/(√3 +1) +( 1/√5+√3 )+ (1/√7+√5)+.+{1/√(2n+1)+√(2n-1)}
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1.1/1*2+1/2*3+1/3*4+……+1/n(n+1) 2.1/1*3+1/3*5+1/5*7+……+1/(2n