What is the roster form of R={x: x is an integer and x²=4}?
Answer and explanation
Correct answer: R={-2,2}
The governing concept is solving a quadratic condition over the stated domain. From x²=4, taking square roots gives x=2 or x=-2, since both 2²=4 and (-2)²=4. Both values are integers, so both belong in the roster. The number 4 is the square value, not a solution for x. Therefore option C is correct; A and B omit one valid solution, while D confuses x with x².
Frequently asked questions
What is the correct answer to this question?
R={-2,2}
Why is this the correct answer?
The governing concept is solving a quadratic condition over the stated domain. From x²=4, taking square roots gives x=2 or x=-2, since both 2²=4 and (-2)²=4. Both values are integers, so both belong in the roster. The number 4 is the square value, not a solution for x. Therefore option C is correct; A and B omit one valid solution, while D confuses x with x².
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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