Let A = {x ∈ ℤ : x is a power of 2 and x < 0}. What is A?
Answer and explanation
Correct answer: A = ∅
Every integral power of 2 is positive: for any integer n, 2ⁿ > 0, including negative exponents such as 2⁻¹ = 1/2. Therefore no power of 2 can satisfy x < 0. Since the set contains no element, it is the empty set, written as ∅. The negative numbers listed in option B are not powers of positive 2.
Frequently asked questions
What is the correct answer to this question?
A = ∅
Why is this the correct answer?
Every integral power of 2 is positive: for any integer n, 2ⁿ > 0, including negative exponents such as 2⁻¹ = 1/2. Therefore no power of 2 can satisfy x < 0. Since the set contains no element, it is the empty set, written as ∅. The negative numbers listed in option B are not powers of positive 2.
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.