What are the roots of the equation \(3x^2=12\) when it is solved by the square-root method?
Answer and explanation
Correct answer: \(x=\pm2\)
Dividing the equation by 3 gives \(x^2=4\). Taking square roots, \(x=\pm\sqrt{4}=\pm2\), so the two roots are 2 and −2. Options B and C show only one of the two roots, while option D results from an incorrect square-root calculation. Exam tip: whenever \(x^2=a\), write \(x=\pm\sqrt{a}\) to include both roots.
Frequently asked questions
What is the correct answer to this question?
\(x=\pm2\)
Why is this the correct answer?
Dividing the equation by 3 gives \(x^2=4\). Taking square roots, \(x=\pm\sqrt{4}=\pm2\), so the two roots are 2 and −2. Options B and C show only one of the two roots, while option D results from an incorrect square-root calculation. Exam tip: whenever \(x^2=a\), write \(x=\pm\sqrt{a}\) to include both roots.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Methods of Solving Quadratic Equations.
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