1) If ab=r mod p, where r is a quadratic residue of the odd prime p, prove that a & b are both quadratic residues of p or both non-residues of p.

2) If a and b are both quadratic residues of the odd prime p, or both non-residues of p, show that the congruence ax^{2}=b mod p has a solution [hint: multiply the given congruence by a', where aa'=1 mod p]

Need all the help i can get... pretty stuck. Thanks !