Suppose that r is a solution of the equation:

anxn + a(n−1)x(n−1) + . . . + a1x + a0 = 0

where the coefficients ak belongs to Z for k = 0, 1, . . . n, and n is greater or equal to 1. If r is a rational solution r = p/q, where p, q belong to Z and p and q are

coprime, show that q|an and p|a0.

Im not even sure where to begin, im so confused, what am i trying to prove? and how do i prove it.