A89: Summation bug???


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A89: Summation bug???




I seem to be having a bit of trouble with the summation function on the 
TI-89...seems pretty simple, too.  Anyway, I typed in 
"E((-1/2)^n*x^(2*n)/n!|x=2,n,0,2)" and it returns "3*2^n*(-1)^n/(n!)" (the 
'E' is a capitol sigma).  However, when I physically replace x with 2 in the 
expression (and subsequently delete the "|x=2" part), it returns the correct 
answer of 1.  How come there's 'n's in the returned expression of the first 
entry?  Shouldn't the "with" operator ( | ) have replaced all occurences of x 
in the subexpression with 2?

JayEll



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