Problem showing f is monotonic

Itay4

New member
Joined
May 23, 2015
Messages
2
Hey,

Here is the question:

f is a continuous function.
|f| is monotonically increasing.
I need to prove that f is monotonic.

i thought starting with showing that f(x) is not 0 for any x, but didn't quite got anywhere.

Any lead will be highly appreciated.

Thanks!
 
f is a continuous function.
|f| is monotonically increasing.
I need to prove that f is monotonic.

i thought starting with showing that f(x) is not 0 for any x, but didn't quite got anywhere.

Any lead will be highly appreciated.
Might this be a useful lead? ;)
 
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