Limits with symbols won't calculate

Questions
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1

Hey there

I have the following function:

Capture.PNG

But when i use limit on it then this happen:

Capture2.PNG
Capture2.PNG405×121 8.64 KB

If i do it in hand, then i get that the limit is De when R → infinity, but why can’t Mathematica find that ?

Regards Andreas

2

Hi,
How can you find the limit without knowing what a is? Also you have square brackets where they should be round and you should use lower case so you don’t bump into reserved symbols.

In[11]:= Limit[de (1 - Exp[-a (r - re)])^2, r -> Infinity, 
 Assumptions -> a < 0]

Out[11]= ComplexInfinity

In[12]:= Limit[de (1 - Exp[-a (r - re)])^2, r -> Infinity, 
 Assumptions -> a > 0]

Out[12]= de
3

Hey

Ah ye “a” is an positive constant (sorry forgot to say that), but thx for the reply and that should solve my problem :slight_smile: