If the second derivative of a function is constant on some interval, you can bound the maximum of this function's absolute value from below in terms of this constant.
What does the above statement mean?
If $f(x)=ax^2+bx+c\implies f''(x)=2a$
Does the above statement mean $|f(x)|\ge2a?$
My main intention is to understand the answer posted on this thread.