ComedkApplication Of DerivativesCOMEDK 2025 Evening ShiftMCQ+1 / -02025Let $f(x)=x \sqrt{4 a x-x^2}, a>0$ then $f^{\prime}(x)$ at $x=2 a$ is :A Does not existB ZeroC DecreasingD IncreasingCheck AnswerClear SelectionReveal AnswerShow Explanation