The definition of integral is a summation formula, which is exactly the same as series. If the integrand function of a generalized integral is always greater than 0, then it can definitely be regarded as a positive series. As long as the definition of integral is used to write integral, it is a positive series.

However, this is only a principle. To explain "how to push" to you, you must introduce the definition and transformation method of series. There is too much content. Whether you can do it or not depends on your understanding of basic concepts.