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# How to write the ± (plus/minus character)?

Posted 10 years ago
 Hi! I have to solve a limit, so i wrote:lim (x^2+1)/(x+1) as x->±infbut the ± is not being recognized, how can i write it?Thank you for your time!
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Posted 10 years ago
 Many of Mathematica's characters have multiple ways of entering them, but a nice trick to remember is that the TeX code for the character with an escape before and after often works.In this case, esc + \pm + esc does the trick
Posted 10 years ago
 You have alsoDirectedInfinityDirectedInfinity[-1]DirectedInfinity[Cos[a] + I Sin[a]]for a real variable a at your disposal. Q: Is there also a DirectedInfinity?
Posted 10 years ago
 I'm using wolfram alpha, and ended up doing it 2 times, one for infinity, and one for -infinity. Thank you for your answer!
Posted 10 years ago
 Hi, are you using Mathematica or Wolfram|Alpha?It's possible to enter this symbol into Mathematica:[url=] reference.wolfram.com/mathematica/ref/PlusMinus.htmlYou can enter it into Mathematica by typing:\[PlusMinus]It is a symbol without any built-in meaning. You can define a meaning for it, but without it, Mathematica will not know what to do with it:http://reference.wolfram.com/mathematica/tutorial/OperatorsWithoutBuiltInMeanings.htmlI would evaluate the limit with both positive and negative infinity separately instead of defining the operator. If you are looking to use Wolfram|Alpha, this has been asked once before here.In short, you can't use Plus-Minus with Wolfram|Alpha. Enter each query individually:lim (x^2+1)/(x+1) as x->infinitylim (x^2+1)/(x+1) as x->-infinity