Which is the roster form of Y₁ = {x : x is an integer from 1 to 20 and x is divisible by neither 2 nor 3}?
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Answer and explanation
Correct answer: Y₁ = {1, 5, 7, 11, 13, 17, 19}
List the integers from 1 through 20 and reject every number divisible by 2 or by 3. The numbers divisible by 2 are all even numbers, while the multiples of 3 include 3, 6, 9, 12, 15, and 18. The numbers that belong to neither group are 1, 5, 7, 11, 13, 17, and 19, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
Y₁ = {1, 5, 7, 11, 13, 17, 19}
Why is this the correct answer?
List the integers from 1 through 20 and reject every number divisible by 2 or by 3. The numbers divisible by 2 are all even numbers, while the multiples of 3 include 3, 6, 9, 12, 15, and 18. The numbers that belong to neither group are 1, 5, 7, 11, 13, 17, and 19, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
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