Answer to Question #212583 in Algebra for krizaagustiire

Question

Consider the following sets, with U = N; that is, the universal set is the setof natural numbers:A = {x | x2 = 25}, B = {x | x = n2, 1 < n < 5} ,C = {1, 3, 5, 7, 9, 11, 13,...}Which of the following is equal to A ∪ C?
A. ∅B. {5}C. {−5, 5}D. Set C

Answer 1

I think that the correct answer is D because as a result, the operation union (U) means the set which contains all the elements from two sets-operands. The set C, as we can see, represents the set of all odd natural numbers. The set A means all numbers, its square is 25. So all the numbers from A are odd. So we proved that the set A have only odd numbers and, consequently, it is the subset of all odd natural numbers, C. And we add the elements of two sets. The natural numbers should be considered in a solution of the question. So we have set C as a result the union of A and C because A is subset of C on the set of natural numbers, all the elements from A are already in C, so C is the result of the union of two sets.