Which set is equal to A = {x ∈ ℤ : x³ = x}?
Answer and explanation
Correct answer: A = {−1, 0, 1}
We solve the defining equation x³ = x by bringing all terms to one side: x³ − x = 0. Factoring gives x(x² − 1) = 0, and then x(x − 1)(x + 1) = 0. Thus x can be 0, 1, or −1. Each of these is an integer and satisfies the original equation. Since a set lists each element only once, A = {−1, 0, 1}.
Frequently asked questions
What is the correct answer to this question?
A = {−1, 0, 1}
Why is this the correct answer?
We solve the defining equation x³ = x by bringing all terms to one side: x³ − x = 0. Factoring gives x(x² − 1) = 0, and then x(x − 1)(x + 1) = 0. Thus x can be 0, 1, or −1. Each of these is an integer and satisfies the original equation. Since a set lists each element only once, A = {−1, 0, 1}.
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.