kill(all)$

van=facebook.com/LearningCalculus$

a(x,y):=(2*x+y^2)/(y+2)$
b(x,y):=(2*x-y^2)/(y-2)$
c(x,y):=2*a(x,y)^(1/3)+2*b(x,y)^(1/3)+1$
d(x,y):=(c(x,y))^2+4*(y-14)$
e(x,y):=d(x,y)^(1/6);

e(x,y);

e(sqrt(13),sqrt(5));

float(e(sqrt(13),sqrt(5)));

float(1+sqrt(5))/2;