M is given by = 1 2 ( sup | ( ) | ) ( sup 1 | ( ) | ) . {\displaystyle M={\frac {1}{2}}\left(\sup _{x\in I}\vert f''(x)\vert ight)\left(\sup _{x\in I}{\frac {1}{\vert f'(x)\vert }} ight).\,}