kill(all)$

Van = facebook.com/LearningCalculus;

f(x,y):=x^(log(y)/log(8)) +y^(log(x)/log(8))-4$ f(x,y);

g(x,y):=(3/2)*(log(x)/log(8))-(3/2)*(log(y)/log(8))-1$ g(x,y);

error(x,y):=f(x,y)-g(x,y);

error((1/2),1/2);

float(error(1/2,1/8));

float(error(8,2));