If D={x: x is a digit and x>6}, what is its roster form?
Answer and explanation
Correct answer: D={7,8,9}
The governing concept is listing elements from a restricted domain. The decimal digits are 0, 1, 2, ..., 9. Among them, the digits strictly greater than 6 are 7, 8, and 9, so D={7,8,9}. The strict sign excludes 6, and 10 is not a digit even though it is greater than 6. Therefore option A is correct; B includes 6 and D violates the digit condition.
Frequently asked questions
What is the correct answer to this question?
D={7,8,9}
Why is this the correct answer?
The governing concept is listing elements from a restricted domain. The decimal digits are 0, 1, 2, ..., 9. Among them, the digits strictly greater than 6 are 7, 8, and 9, so D={7,8,9}. The strict sign excludes 6, and 10 is not a digit even though it is greater than 6. Therefore option A is correct; B includes 6 and D violates the digit condition.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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