Find the point of diminishing returns \((x,y)\) for the function \(R(x)\), where \(R(x)\) represents revenue (in thousands of dollars) and \(x\) represents the amount spent on advertising (in thousands of dollars).
\(R(x) = 11,000 - x^3 + 42x^2 + 800x, \quad 0 \le x \le 20\)
The point of diminishing returns is \(\boxed{\qquad}\) (Type an ordered pair.)
