Which set is A = {x ∈ ℕ : x² < 2x} equal to?
Answer and explanation
Correct answer: A = {1}
Rewrite the inequality as x² − 2x < 0, or x(x − 2) < 0. Over the real numbers, this holds when 0 < x < 2. The natural numbers in this open interval depend on the usual school convention ℕ = {1, 2, 3, …}; only x = 1 belongs to it. Therefore, A = {1}. Neither 0 nor 2 satisfies the strict inequality.
Frequently asked questions
What is the correct answer to this question?
A = {1}
Why is this the correct answer?
Rewrite the inequality as x² − 2x < 0, or x(x − 2) < 0. Over the real numbers, this holds when 0 < x < 2. The natural numbers in this open interval depend on the usual school convention ℕ = {1, 2, 3, …}; only x = 1 belongs to it. Therefore, A = {1}. Neither 0 nor 2 satisfies the strict inequality.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.