Find the minimum of \(x-y\) among all ordered pairs of real numbers \((x,y)\), \(x \) and \(y \) between 0 and 1, where there exists a real number \(a \neq 1\) such that \( \log_{x}a + \log_{y}a = 4\log_{xy}a\)
The minimum value of x - y is 2.
+428 
