isro exam december 2017

Question

The number of elements in the power set of {{1,2},{2,1,1},{2,1,1,2}} is:

Comments

may be they are taking {2,1,1} as {1,2} because set does not allow duplicates(until it is not multiset), but it should be explicitly mentioned.

---

yesss!! I think u r right.. They didn't mentioned it though.. but yes as set doesn't contains any duplicate elements,the whole set will be just {{1,2}}.. Therefore, number of elements will be 2.

Thank you XD

---

yeah 2 is correct

SET is a collection of distinct objects

P(S) = { $\phi$ , {2,1}}

Answer 1

since as we know that in set no element is repeated, now in each set if u remove repeatation  then u will get {{1,2},{1,2},{1,2}} since it has again repeatation again u need to remove repeatation then finally u will get {{1,2}} now powerset will be {phi,{1,2}}

Answer 2

There are three elements in the set. Hence, number of elements in the power set = 2^3 = 8