Ok, i have go to a point working through a question where i am having to show that the LHS = RHS but cant seem to.... is the following possible or have i gone wrong somewhere earlier in my calculations?

If P(Ak) = a + b*$\displaystyle ({q/p})^k$

Then use the equivalent formula for P(Ak+1) and P(Ak-1) and show that....

P(Ak+1) = $\displaystyle \frac{P(Ak) - q*P(Ak-1)}{p}$