[mef]

these days it looks like ChatGPT generates and runs code behind the scenes for math questions (it used to be pretty bad at these kinds of math questions. you can click the little "view analysis" button to see the code it's running.

when I ask about this question it generates and runs Python behind the scenes, thus the incorrect answer.

[lo_zamoyski]

Although it offers an explanation, which is something it could not do by just evaluating the expression. So the explanation is in its training set. And given that this is an understood flaw or limitation, it is possible it didn't even need to run any code.