Recent content by pebloy

The answer is NO: Suppose the statement is true. Then f(x)>0, f''(x)<0 for all x>0 . Moreover, \lim_{x\rightarrow +\infty} f''(x)<0 if it exists. Let f(0)>0, f'(x) is monotonically decreasing, then \lim_{x\rightarrow +\infty} f'(x) is either -\infty or a constant. If...

Sorry I reversed the inequality. :-)

Any positive constant funtion works.