If U = {1, 2, ..., 18}, A = {2, 4, 6, 8, 10, 12}, and B = {6, 9, 12, 15, 18}, what is (B − A)'?
Answer and explanation
Correct answer: {1,2,3,4,5,6,7,8,10,11,12,13,14,16,17}
First calculate the difference B − A. The elements 6 and 12 occur in both sets, so they are removed from B, leaving B − A = {9, 15, 18}. The complement is taken with respect to U = {1, ..., 18}; therefore remove 9, 15, and 18 from U. The result is {1,2,3,4,5,6,7,8,10,11,12,13,14,16,17}, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
{1,2,3,4,5,6,7,8,10,11,12,13,14,16,17}
Why is this the correct answer?
First calculate the difference B − A. The elements 6 and 12 occur in both sets, so they are removed from B, leaving B − A = {9, 15, 18}. The complement is taken with respect to U = {1, ..., 18}; therefore remove 9, 15, and 18 from U. The result is {1,2,3,4,5,6,7,8,10,11,12,13,14,16,17}, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Complement of a Set and Its Properties.
