What is the discriminant \(D\) of the equation \(x^2+4x+4=0\)?
Answer and explanation
Correct answer: 0
For a quadratic equation \(ax^2+bx+c=0\), the discriminant is \(D=b^2-4ac\). Here, \(a=1\), \(b=4\), and \(c=4\). Therefore, \(D=4^2-4(1)(4)=16-16=0\). The value 16 results from forgetting to subtract \(4ac\), while -16 comes from using an incorrect sign. Thus, 0 is correct, and the equation has real and equal roots. Exam tip: identify \(a\), \(b\), and \(c\), including their signs, before substituting them into the formula.
Frequently asked questions
What is the correct answer to this question?
0
Why is this the correct answer?
For a quadratic equation \(ax^2+bx+c=0\), the discriminant is \(D=b^2-4ac\). Here, \(a=1\), \(b=4\), and \(c=4\). Therefore, \(D=4^2-4(1)(4)=16-16=0\). The value 16 results from forgetting to subtract \(4ac\), while -16 comes from using an incorrect sign. Thus, 0 is correct, and the equation has real and equal roots. Exam tip: identify \(a\), \(b\), and \(c\), including their signs, before substituting them into the formula.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Roots of a Quadratic Equation.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
