suppose \(\text{An}\left(x\right)\leq 0\), then\(\int_1^{\infty}f(x)dx:C\Rightarrow\sum_{n=1}^{\infty}An:C\)\(\int_1^{\infty}f(x)dx:C\Rightarrow\sum_{n=1}^{\infty}An:D\)
\(\int_1^{\infty}f(x)dx:C\Rightarrow\sum_{n=1}^{\infty}An:C\)\(\int_1^{\infty}f(x)dx:C\Rightarrow\sum_{n=1}^{\infty}An:D\)