#Prove/disprove subset
19 messages · Page 1 of 1 (latest)
- Wait patiently for a helper to come along.
- Once someone helps you, say thank you and close the thread with:
+close
- Feel free to nominate the person for helper of the week in #helper-nominations
- Do not ping the mods, unless someone is breaking the rules.
- If you're happy with the help you got here, and the server overall, you can contribute financially as well:
Well for any set A and B A\B= A ∩ Comp(B)
With Comp(B) standing for the complementary of B
Then you can maybe use Morgan’s formula
$\overline{A\setminus\qty(B\cup C)}=\overline{A\cap\overline{\qty(B\cup C)}}$
Romans 12:19
im not supposed to throw solutions lmao
you can use one of the De Morgan's laws of sets from here onwards @rich marlin
remember the complement of an intersection?
Yes, I got A' ∪ (B ∪ C) with set difference and De Morgan's law, but the right hand side is A' ∩ (B ∪ C)...
See the union and intersect after A' is different.
and that's why it's disproved.
So I can directly say because it's different, it's disproved? Somehow seems too simple for a 5 marks qns...
give a counterexample too if u like\
Not sure how counter example for set theory looks like, my prof haven't shown any counter examples etc so far... All he ever said was to prove a subset, just show that everything in the first set is in the second set and that's all...
i mean, it'd suffice to say that the equality doesn't hold true always since intersection and union are different operations.
a counterexample'd work like: we may find anyy 3 sets A,B,C that do not satisfy the equation, thus it does not hold for all the A,B,C it claims to hold for