If \(p(x)=x^2+9\), how many times will its graph cut the x-axis?
Answer and explanation
Correct answer: Zero times
Reason: For real x, \(x^2\ge0\), so \(x^2+9\ge9>0\). Thus \(x^2+9=0\) has no real solution and the parabola never meets the x-axis. Using the discriminant: \(D=b^2-4ac=0^2-4\cdot1\cdot9=-36<0\), confirming no real roots. The closest distractor “Two times” is wrong because a quadratic has two x-intercepts only when \(D>0\). Exam tip: check the discriminant or the vertex/minimum value to decide intersection with the x-axis quickly.
Frequently asked questions
What is the correct answer to this question?
Zero times
Why is this the correct answer?
Reason: For real x, \(x^2\ge0\), so \(x^2+9\ge9>0\). Thus \(x^2+9=0\) has no real solution and the parabola never meets the x-axis. Using the discriminant: \(D=b^2-4ac=0^2-4\cdot1\cdot9=-36<0\), confirming no real roots. The closest distractor “Two times” is wrong because a quadratic has two x-intercepts only when \(D>0\). Exam tip: check the discriminant or the vertex/minimum value to decide intersection with the x-axis quickly.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Geometrical meaning of the zeroes of a polynomial..
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