Let a > b > 0, a square + b square + 6 AB equal to 0, then the value of B-A on a + B ratio is equal to 0

Let a > b > 0, a square + b square + 6 AB equal to 0, then the value of B-A on a + B ratio is equal to 0

a²+b²-2ab=4ab
(a-b)²=4ab
a>b>0
So b-ab > 0
a+b=√(8ab)
So the original formula = - √ (8ab / 4AB) = - √ 2