Math Problem Statement

Graph the equation y = x^2 - 9 by plotting points and verify the results using a graphing utility.

Solution

The equation you are tasked with graphing is:

y=x29y = x^2 - 9

This is a quadratic equation, which will produce a parabola when graphed. The general form of a quadratic equation is y=ax2+bx+cy = ax^2 + bx + c, where in your case, a=1a = 1, b=0b = 0, and c=9c = -9.

Steps to graph the equation:

  1. Vertex: The vertex of the parabola occurs at the point (0,9)(0, -9). This is because the quadratic is in the form y=x2+cy = x^2 + c, where the vertex lies at x=0x = 0, and y=9y = -9.

  2. Plot Points:

    • When x=3x = -3 or x=3x = 3, y=0y = 0 (these are the x-intercepts).
    • When x=2x = 2 or x=2x = -2, y=5y = -5.
    • When x=1x = 1 or x=1x = -1, y=8y = -8.
  3. Symmetry: Since this is a parabola, it is symmetric about the y-axis (i.e., for every point (x,y)(x, y), there is a corresponding point (x,y)(-x, y)).

  4. Graph Shape: The parabola opens upwards because the coefficient of x2x^2 is positive.

Key points to plot:

  • (0,9)(0, -9) (the vertex)
  • (3,0)(3, 0) and (3,0)(-3, 0) (the x-intercepts)
  • (2,5)(2, -5), (2,5)(-2, -5)
  • (1,8)(1, -8), (1,8)(-1, -8)

Once you have these points, you can draw a smooth curve through them to form the parabola.

Would you like a detailed explanation on how to compute each point, or do you have any other questions?

Here are 5 questions you could consider for further exploration:

  1. How do we determine the axis of symmetry for any quadratic equation?
  2. What happens to the graph if we change the constant in the equation (e.g., y=x25y = x^2 - 5)?
  3. How can we find the vertex of a quadratic equation algebraically?
  4. What is the role of the leading coefficient in determining the direction of a parabola?
  5. How do we determine the x-intercepts algebraically?

Tip: When graphing quadratic functions, always start by finding the vertex, as it provides the center of symmetry for the parabola.

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Graphing Parabolas

Formulas

y = ax^2 + bx + c

Theorems

Vertex of a Parabola
Axis of Symmetry

Suitable Grade Level

Grades 9-10