Which of the following values is not a root of the equation \(x^2-16=0\)?
Answer and explanation
Correct answer: 0
Factor the equation: \((x-4)(x+4)=0\), so the roots are \(x=4\) and \(x=-4\). Substituting \(x=0\) gives \(0^2-16=-16\neq0\), so 0 is not a root. A common trap is \(\sqrt{16}\), which equals 4 and hence is a root; note that \(\sqrt{16}\) denotes the principal (positive) square root. Exam tip: always check by substitution or factoring to confirm whether a candidate value satisfies the equation.
Frequently asked questions
What is the correct answer to this question?
0
Why is this the correct answer?
Factor the equation: \((x-4)(x+4)=0\), so the roots are \(x=4\) and \(x=-4\). Substituting \(x=0\) gives \(0^2-16=-16\neq0\), so 0 is not a root. A common trap is \(\sqrt{16}\), which equals 4 and hence is a root; note that \(\sqrt{16}\) denotes the principal (positive) square root. Exam tip: always check by substitution or factoring to confirm whether a candidate value satisfies the equation.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Roots of a Quadratic Equation.
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