If T = {x : x is a two-digit number whose digits are equal}, what is the roster form of T?
Answer and explanation
Correct answer: T = {11, 22, 33, 44, 55, 66, 77, 88, 99}
A two-digit number has a tens digit and a units digit, and the condition requires these two digits to be identical. The possible repeated digits are 1 through 9, giving 11, 22, 33, 44, 55, 66, 77, 88, and 99. The number 1 is excluded because it has only one digit, while numbers such as 12 have unequal digits. Therefore, option A is the correct roster form.
Frequently asked questions
What is the correct answer to this question?
T = {11, 22, 33, 44, 55, 66, 77, 88, 99}
Why is this the correct answer?
A two-digit number has a tens digit and a units digit, and the condition requires these two digits to be identical. The possible repeated digits are 1 through 9, giving 11, 22, 33, 44, 55, 66, 77, 88, and 99. The number 1 is excluded because it has only one digit, while numbers such as 12 have unequal digits. Therefore, option A is the correct roster form.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
