用数学归纳法证明:1+1/2∧2+1/3∧2+……+1/n∧2≥(3n)/(2n+1)

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用数学归纳法证明:1+1/2∧2+1/3∧2+……+1/n∧2≥(3n)/(2n+1)

用数学归纳法证明:1+1/2∧2+1/3∧2+……+1/n∧2≥(3n)/(2n+1)
用数学归纳法证明:1+1/2∧2+1/3∧2+……+1/n∧2≥(3n)/(2n+1)

用数学归纳法证明:1+1/2∧2+1/3∧2+……+1/n∧2≥(3n)/(2n+1)
既然是数学归纳法..应该很简单了..
当n=1时,3n/(2n+1)=1,满足;
若n=k时成立(k≥1),则1+1/2^2+1/3^2+…+1/k^2≥3k/(2k+1);
则1+1/2^2+…+1/k^2+1/(k+1)^2≥3k/(2k+1)+1/(k+1)^2;
3k/(2k+1)+1/(k+1)^2-(3k+3)/(2k+3)=(k^2+2k)/((k+1)^2*(2k+1)*(2k+3))>0,
故1+1/2^2+…+1/k^2+1/(k+1)^2>(3k+3)/(2k+3),
即n=k+1时也成立.
over.