10/15/2015, 12:12 PM

I was thinking about the sign of the n th Derivative.

More precisely real analytic for x>0 where the expansion point Goes from 0 to + oo.

Sine and cosine are simple.

But for other cases , when the expansion point Goes to + oo it is less trivial.

For instance - too give a quite general case -

What about e.g.

D^a(n) f(b(m)) < 0

D^a2(n) f(b2(m)) > 0.

What are the solutions and how to find them easily ?

Maybe this is easy sorry.

I havent thought about it much.

Regards

Tommy1729

More precisely real analytic for x>0 where the expansion point Goes from 0 to + oo.

Sine and cosine are simple.

But for other cases , when the expansion point Goes to + oo it is less trivial.

For instance - too give a quite general case -

What about e.g.

D^a(n) f(b(m)) < 0

D^a2(n) f(b2(m)) > 0.

What are the solutions and how to find them easily ?

Maybe this is easy sorry.

I havent thought about it much.

Regards

Tommy1729