1.II.16A

Complex Methods
Part IB, 2004

Let pp and qq be two polynomials such that

q(z)=l=1m(zαl)q(z)=\prod_{l=1}^{m}\left(z-\alpha_{l}\right)

where α1,,αm\alpha_{1}, \ldots, \alpha_{m} are distinct non-real complex numbers and degpm1\operatorname{deg} p \leqslant m-1. Using contour integration, determine

p(x)q(x)eixdx\int_{-\infty}^{\infty} \frac{p(x)}{q(x)} e^{i x} d x

carefully justifying all steps.