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I'm new to mathematica and have trouble simplifying an expression.

I want to simplify the expression:

Exp[-s*t]

under the constraint that t=+Inf and s is a positive real number. I try it using:

Simplify[Exp[-s*t], {t = +Infinity, Element[s, PositiveReals]}]

However, it will get simplified to

E^(s (-\[Infinity]))

instead of the desired

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Why is this ?

(btw.: I'm using Mathematica 9)

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  • $\begingroup$ try ` Simplify[-x*(Exp[-2*s*t] - 1) == x /. t -> Infinity,Element[s, PositiveReals]]`? $\endgroup$
    – kglr
    Mar 10, 2021 at 17:45
  • $\begingroup$ still "x - E^(s (-[Infinity])) x == x". Please note, that I simplified the expression in the question to make the problem more obvious. $\endgroup$
    – Lenny
    Mar 10, 2021 at 17:51
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    $\begingroup$ Either Assuming[s > 0, x - E^(s (-\[Infinity])) x == x // Simplify] or Simplify[x - E^(s (-\[Infinity])) x == x, s > 0] evaluate to True $\endgroup$
    – Bob Hanlon
    Mar 10, 2021 at 18:10

1 Answer 1

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Try this:

Simplify[Exp[-s*t] /. t -> \[Infinity], s > 0]

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Have fun!

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