Which of the following quadratic equations has discriminant -47?
Answer and explanation
Correct answer: x^2+x+12=0
Discriminant is defined by \(D=b^2-4ac\). For option A, \(a=1,\;b=1,\;c=12\), so \(D=1^2-4\cdot1\cdot12=1-48=-47\), which matches. The closest distractor, option D, gives \(D=(-8)^2-4\cdot1\cdot30=64-120=-56\), not -47. Exam tip: always identify \(a,b,c\) first and compute \(b^2-4ac\) carefully, watching signs of b and c.
Frequently asked questions
What is the correct answer to this question?
x^2+x+12=0
Why is this the correct answer?
Discriminant is defined by \(D=b^2-4ac\). For option A, \(a=1,\;b=1,\;c=12\), so \(D=1^2-4\cdot1\cdot12=1-48=-47\), which matches. The closest distractor, option D, gives \(D=(-8)^2-4\cdot1\cdot30=64-120=-56\), not -47. Exam tip: always identify \(a,b,c\) first and compute \(b^2-4ac\) carefully, watching signs of b and c.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Introduction to Quadratic Equations.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
