If A₁ = {x : x ∈ ℤ and x² = 2}, what is A₁?
Answer and explanation
Correct answer: Empty set
Solving x² = 2 over the real numbers gives x = √2 and x = −√2. Neither value is an integer, because √2 is irrational. The condition x ∈ ℤ restricts us to integers only, so no value satisfies both requirements. Therefore A₁ contains no elements and is the empty set, A₁ = ∅.
Frequently asked questions
What is the correct answer to this question?
Empty set
Why is this the correct answer?
Solving x² = 2 over the real numbers gives x = √2 and x = −√2. Neither value is an integer, because √2 is irrational. The condition x ∈ ℤ restricts us to integers only, so no value satisfies both requirements. Therefore A₁ contains no elements and is the empty set, A₁ = ∅.
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.