巧用拉格朗日中值定理

Skillfully Using Lagrangian Middle-Value Theorem

巧用拉格朗日中值定理确定方程的根的存在性、求函数极限以及研究函数在区间上的性态、证明调和级数的敛散性、证明不等式和恒等式。

The paper proves the congruity series convergent and exhale character,confirms an equation root,extracts the function limit In this,study function at district character,proves the in equation and equation,skillfully using Lagrangian middle value theorem.