Determine all strictly increasing functions that satisfies the conditions:
Solution
Answer. Solution does not exist.
Let us substitute at the first condition .
Then when and when we obtain such equations:
Since is strictly increasing:
If we substitute and , we obtain
Since can equal any positive value (from the second condition), the last equation can be rewritten in such a way: , where .
Therefore, is increasing and satisfies Cauchy's functional equation, thus for some real . After checking the first condition it is clear that only case is correct, but such a function does not satisfy the second condition.
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