Consider the function f(x) = | x² $$-$$ 5x + 6 |

What is f'(4) equal to?

Consider the function f(x) = | x² $$-$$ 5x + 6 |

What is f''(2.5) equal to ?

If $$y = {(\cos x)^{{{(\cos x)}^{(\cos x)\infty }}}}$$, then $${{dy} \over {dx}}$$ is equal to

Consider the following statements

1. Derivative of f(x) may not exist at some point.

2. Derivative of f(x) may exist finitely at some point.

3. Derivative of f(x) may be infinite (geometrically) at some point.

Which of the above statements are correct?