x = 1+2^p 2^p = x-1y = 3^(-q) y = 1/3^q 3^q = 1/yz = [1+2^(-p)] + 27^q= [1+1/2^p ] + 3^(3q)= [1+1/(x-1) ]+ (3^q)^3= [1+1/(x-1) ]+ (1/y)^3= 1+1/(x-1) + y^(-3)