What is L = {x ∈ ℕ : x is a two-digit number and the sum of its digits is 3}?
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Answer and explanation
Correct answer: L = {12, 21, 30}
Let the tens digit be a and the units digit be b. For a two-digit number, a is at least 1, and a + b = 3. The possible digit pairs are (1,2), (2,1), and (3,0), producing 12, 21, and 30. The number 3 is not two-digit, and 11 has digit sum 2. Therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
L = {12, 21, 30}
Why is this the correct answer?
Let the tens digit be a and the units digit be b. For a two-digit number, a is at least 1, and a + b = 3. The possible digit pairs are (1,2), (2,1), and (3,0), producing 12, 21, and 30. The number 3 is not two-digit, and 11 has digit sum 2. Therefore 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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