$ = \int_{-N}^{N} \left | \frac{x^n}{1} \right |\, dx f(x) \,\! $ $ = \sum_{n=0}^\inf a_n x^n $
$ = \left | \frac{a}{b} \right | $
$ = \int_{-N}^{N} \left | \frac{x^n}{1} \right |\, dx f(x) \,\! $ $ = \sum_{n=0}^\inf a_n x^n $
$ = \left | \frac{a}{b} \right | $