Math Problem Statement

The adjoining figure shows the graph of y = ax^2 + bx + c. Which of the following is correct? (i) a > 0 (ii) b > 0 (iii) c > 0 (iv) b^2 < 4ac

Solution

The image shows a graph of the quadratic function y=ax2+bx+cy = ax^2 + bx + c and asks which of the following statements are correct based on the graph:

  1. a>0a > 0
  2. b>0b > 0
  3. c>0c > 0
  4. b2<4acb^2 < 4ac

Analysis:

  • Nature of the Parabola: The graph is a parabola that opens downwards, which means the coefficient of x2x^2 (i.e., aa) must be negative, so a<0a < 0. Therefore, statement (i) is incorrect.

  • Sign of bb: The graph shows a parabola that intersects the x-axis at two distinct points, implying the quadratic equation has two real roots. This suggests that the discriminant b24acb^2 - 4ac must be greater than or equal to zero. If the parabola is symmetrical about the y-axis or shifted, it can provide information about bb. However, without clear asymmetry, determining bb based solely on the graph is challenging.

  • Sign of cc: The y-intercept of the graph is at a positive value on the y-axis, indicating that c>0c > 0. Therefore, statement (iii) is correct.

  • Discriminant Condition b2<4acb^2 < 4ac: Since the parabola intersects the x-axis at two points, the discriminant must satisfy b24ac0b^2 - 4ac \geq 0. This means statement (iv), which states b2<4acb^2 < 4ac, is incorrect.

Conclusion:

The correct answer is (iii) only.

Would you like more details or have any further questions?

Here are some related questions to expand your understanding:

  1. How do you derive the formula for the discriminant of a quadratic equation?
  2. How does the sign of bb affect the position of the vertex of a parabola?
  3. What are the geometric interpretations of the coefficients aa, bb, and cc in a quadratic function?
  4. How does the vertex form of a quadratic equation relate to its standard form?
  5. What conditions on the coefficients ensure that a parabola has no real roots?

Tip: Always analyze the graph's shape and key points (like intercepts and vertex) to determine the signs of the coefficients in a quadratic function.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Discriminant
Graph of Parabolas

Formulas

y = ax^2 + bx + c
Discriminant formula: Δ = b^2 - 4ac

Theorems

Conditions for Real Roots: Δ ≥ 0
Nature of Parabola Opening (a > 0 or a < 0)

Suitable Grade Level

Grades 9-12