What is the roster form of Q={x∈N: x<20 and x has last digit 2}?
Answer and explanation
Correct answer: Q={2,12}
The governing concept is converting a set-builder condition into roster form. Natural numbers less than 20 are 1 through 19. Checking their units digits, only 2 and 12 end in 2. The number 22 is not less than 20, 20 has units digit 0 and also fails the bound, and 10 ends in 0. Therefore the complete set is {2,12}, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
Q={2,12}
Why is this the correct answer?
The governing concept is converting a set-builder condition into roster form. Natural numbers less than 20 are 1 through 19. Checking their units digits, only 2 and 12 end in 2. The number 22 is not less than 20, 20 has units digit 0 and also fails the bound, and 10 ends in 0. Therefore the complete set is {2,12}, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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