判别广义积分敛散性的又一种方法

Another Method of Testing Convergency and Divergency of Generalized Integral

利用被积函数本身具有的性质，即由ｌｉｍｘ→＋∞ｘｆ′（ｘ）ｆ（ｘ）＝Ｌ，根据Ｌ值的不同判别广义积分∫＋∞ａｆ（ｘ）ｄｘ的敛散性。

The convergency and divergency of generalized integral ∫ +∞ af(x)dx are tested here according to different value l got from lim x→+∞xf′(x)f(x)=l by making use of nature of this integrated function itself