来自刘向荣的问题
【证明不等式的高二数学题n∈N+,证明:1<1/(n+1)+1/(n+2)+1/(n+3)+……+1/(3n+1)<2】
证明不等式的高二数学题
n∈N+,证明:
1<1/(n+1)+1/(n+2)+1/(n+3)+……+1/(3n+1)<2
1回答
2019-08-26 09:34
【证明不等式的高二数学题n∈N+,证明:1<1/(n+1)+1/(n+2)+1/(n+3)+……+1/(3n+1)<2】
证明不等式的高二数学题
n∈N+,证明:
1<1/(n+1)+1/(n+2)+1/(n+3)+……+1/(3n+1)<2
令f(n)=1/(n+1)+1/(n+2)+1/(n+3)+……+1/(3n+1)f(n+1)=1/(n+2)+1/(n+3)+1/(n+4)+……+1/[3(n+1)+1]f(n+1)-f(n)=1/(n+1)-1/(3n+2)-1/(3n+3)-1/(3n+4)>0所以函数f(n)对于n为正整数时为单调增函数所...