The similarities between this condition and the definition of the derivative are obvious, but I can't seem to find an approach whereby I can actually prove a derivative exists in this case.A function a,b)\to R" alt="fa,b)\to R" /> satisfies aLipschitz conditionat iff there is and such that and imply that . If is differentiable at , prove that satisfies a Lipschitz condition at .

Any ideas?

Thanks!