So imagine f'(x) was the cubic in the image I have attached above
Is it the fact that f(x), f'(x) and f''(x) are all monotonic increasing
Also for this question below, for 16 and 17 I know how to do it in my head but am not sure how to geometrically prove it
Also for 18, the answer is 6,6 but I got 3
(Image removed from quote.)
For the sake of this question, STOP considering f"(x).
Like I said, WHEN f(x) is INCREASING, the DERIVATIVE f'(x) is POSITIVE.
ALL I want you to note is when f(x) is increasing/decreasing/stationary that f'(x) is above/below/intersecting the x-axis respectively. I think you do not understand what our explanations meant.
For Q18, the correct answer should technically be 6,3. 6,6 is not right in my opinion as there's double counting.