How to graph Taylor series on the Prime

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Quote:F1:=CAS("taylor(sin('X'),('X') = 0,1,polynom)");

First thanks for this forum. Without the information given here I would be lost and the prime would be (almost) useless for me because I have no instructor nor too much time to get used to the device. :-)

Using the above command works in that I enter the command in home view and the resulting series is inserted into the function app. However I wonder why can't I use the exact same command directly as input from within the app?

The single quotes are necessary to have prime identify 'X' as a symbolic variable and no numeric. Am i right? Why would 'x' instead of 'X' not work?
these little quirks are giving me a hard time.