@soupless of course, as you know for any $x,y$ there exist $a,b$ such that $x=a+b$ and $y=a-b$, Of course $a>b>0$ which follows $x>y$. Reason here is : look at the denominator. You can see that after substutition we can cancell quadratic terms. Of course, degree is still $2$. But, at least you could hope last expression may be very simple for to use arithmetic-geometric mean inequality. — lone student Feb 17 at 8:11