Read the following paragraph and answer Q.17 and Q.18.
Let p,q be integers and let α,β be the roots of the equation x2−x−1=0, where α=β. For n=0,1,2,…, let an=pαn+qβn. FACT: If a and b are rational numbers and a+b5=0, then a=0=b.
If a4=28, then p+2q=