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Message "Your union can be simplified by combining some sets" in case if a wrong answer.

by F. Heiderich - Sunday, 3 September 2017, 4:44 AMNumber of replies: 1

In the following problem the student gets the message "Your union can be simplified by combining some sets" if he enters the wrong answer "(-inf,-3) U (1,inf)". In my opinion this is misleading, because it suggests that the answer is right but could be further reduced. Neither of it is the case.

This problem will produce the error message 'Your union can be simplified by combining some sets' when the wrong answer "(-inf,3) U (1,inf)" is entered.

Determine the set of all [``x \in \mathbb{R}``] that fulfill the condition [``x < -3 \text{ and } x > 1``]: [_______________]{"$I1intI2"}.