If A = {x ∈ ℝ : x² = 9} and B = {-3, 3}, choose the correct statement about A.
Answer and explanation
Correct answer: A = B
To determine A, solve x² = 9 over the real numbers. Taking square roots gives x = 3 or x = -3, because both 3² and (-3)² equal 9. Therefore A = {-3, 3}. This is exactly the same collection of elements as B, so A = B. The negative root must not be omitted when solving a square equation.
Frequently asked questions
What is the correct answer to this question?
A = B
Why is this the correct answer?
To determine A, solve x² = 9 over the real numbers. Taking square roots gives x = 3 or x = -3, because both 3² and (-3)² equal 9. Therefore A = {-3, 3}. This is exactly the same collection of elements as B, so A = B. The negative root must not be omitted when solving a square equation.
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.