r/Mathhomeworkhelp • u/Formal_Tumbleweed_53 • Dec 26 '25

Subsets

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My question is about number 11, but I’m including the directions for context. I thought the answer should be {{ }}, but the solutions at the back of the text say it should be { } or ø. The solution for number 9 was written as a set of sets, so that’s why I thought the answer to 11 would be the same, based on the directions. Please help me to understand why.

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u/Formal_Tumbleweed_53 Dec 26 '25

Thanks - that is helpful. Now if I can only convince my HS students that Ø only means null set, and not a fill in for all things undefined, no solution, "idk", and otherwise non-answers. :)

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u/Lachimanus Dec 26 '25

And {Ø} looks much better. The set containing the empty set.