Find all values of such that

**Solution**

*We’re invoking the same technique as in the problem here. *Successively we have:

Obviously is differentiable in and its derivative is

It is . We distinguish cases:

- If then attains global maximum at equal to . Since it follows that .
- If then attains global minimum at equal to . In this case , however , the inequality cannot hold for all ; since is continuous its range is:
Hence this case is rejected.

- For the inequality obviously holds for all .

Summing up , .