The teacher asked us to minimize an expression:, where
Since the denominator and numerator are homogeneous, we try to divide the y^2 into two halves:
Use the inequality
and we get:
also, the same way to find the minima of :
Now we let , that is
But this method is quite troublesome... right?
Is there any other way to solve the minima? I also tried partial derivative, but it's not easy to solve that equation either...