Write E = {x : x ∈ ℤ and x² = 9} in roster form.
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Answer and explanation
Correct answer: E = {−3, 3}
The condition requires integer values of x whose square is 9. Solving x² = 9 gives x = ±√9, so x = 3 or x = −3. Both values are integers and both satisfy the condition because 3² = 9 and (−3)² = 9. Therefore, the roster form must include both solutions: E = {−3, 3}. Zero and ±9 do not satisfy x² = 9.
Frequently asked questions
What is the correct answer to this question?
E = {−3, 3}
Why is this the correct answer?
The condition requires integer values of x whose square is 9. Solving x² = 9 gives x = ±√9, so x = 3 or x = −3. Both values are integers and both satisfy the condition because 3² = 9 and (−3)² = 9. Therefore, the roster form must include both solutions: E = {−3, 3}. Zero and ±9 do not satisfy x² = 9.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
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