Which of the following values is a root of \(x^2+4x=0\)?
Answer and explanation
Correct answer: -4
Factor the expression: \(x^2+4x = x(x+4)\). By the zero-product property, the roots are \(x=0\) and \(x=-4\). Among the given choices \(-4\) is present, so it is correct. For example, substituting \(x=4\) gives \(4^2+4\cdot4=16+16=32\neq0\), so 4 is not a root. Exam tip: always try factoring out the common factor first to apply the zero-product rule quickly.
Frequently asked questions
What is the correct answer to this question?
-4
Why is this the correct answer?
Factor the expression: \(x^2+4x = x(x+4)\). By the zero-product property, the roots are \(x=0\) and \(x=-4\). Among the given choices \(-4\) is present, so it is correct. For example, substituting \(x=4\) gives \(4^2+4\cdot4=16+16=32\neq0\), so 4 is not a root. Exam tip: always try factoring out the common factor first to apply the zero-product rule quickly.
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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