[CAS] limit() question

05252018, 10:27 AM
Post: #1




[CAS] limit() question
I encountered this limit example:
limit(ABS((x2)^(n+1)/((n+1)^2*3^(n+1)) / ((x2)^n/(n^2*3^n))),n,∞); ==> undef During a simplification process, (of the underlying expression), a result is obtained at this equivalent expression: limit(ABS((x2)*n^2/((n+1)^2*3)),n,∞); ==> ABS(x2)/3 Further simplification continues to return ABS(x2)/3. Should the original (unsimplified) expression, also return this result, (instead of "undef")? Dale 

05262018, 06:07 AM
Post: #2




RE: [CAS] limit() question
Yes, undef is expected, because limit does series expansion without simplifications (because simplify could return a much harder limit), and you can not do that for (x2)^n without assumption on x (need to know the sign of ln(x2)). If you run for example assume(x>3) the initial limit will be solved. Or if you run simplify, because it will remove the (x2)^n.


05262018, 08:19 AM
Post: #3




RE: [CAS] limit() question
Thank you for your explanation, Parisse.
Dale 

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