Math Problem Statement

y=x²-x-12 solve by graphical mehod

Solution

To solve the quadratic equation y=x2x12y = x^2 - x - 12 using the graphical method, follow these steps:

1. Identify the quadratic function:

The equation represents a parabola: y=x2x12y = x^2 - x - 12

2. Find the x-intercepts (roots):

The x-intercepts occur when y=0y = 0, meaning we need to solve: x2x12=0x^2 - x - 12 = 0

To solve by factoring: x2x12=(x4)(x+3)=0x^2 - x - 12 = (x - 4)(x + 3) = 0

Thus, the solutions are: x=4andx=3x = 4 \quad \text{and} \quad x = -3 So, the parabola intersects the x-axis at x=4x = 4 and x=3x = -3.

3. Find the vertex:

The vertex of the parabola occurs at the axis of symmetry, given by the formula: x=b2ax = \frac{-b}{2a} For the equation y=ax2+bx+cy = ax^2 + bx + c, here a=1a = 1, b=1b = -1, and c=12c = -12: x=(1)2(1)=12=0.5x = \frac{-(-1)}{2(1)} = \frac{1}{2} = 0.5 Substitute x=0.5x = 0.5 into the equation to find the y-coordinate of the vertex: y=(0.5)20.512=0.250.512=12.25y = (0.5)^2 - 0.5 - 12 = 0.25 - 0.5 - 12 = -12.25 Thus, the vertex is at (0.5,12.25)(0.5, -12.25).

4. Plot the parabola:

  • The parabola opens upwards because the coefficient of x2x^2 is positive.
  • Plot the x-intercepts at x=4x = 4 and x=3x = -3.
  • Plot the vertex at (0.5,12.25)(0.5, -12.25).
  • Sketch the curve through these points, ensuring the parabola is symmetric around the vertex.

5. Interpret the roots:

From the graph, the x-intercepts x=4x = 4 and x=3x = -3 are the solutions to the quadratic equation.

Do you want details on how to graph this using software or further elaboration?

Here are 5 related questions:

  1. What are other methods to solve quadratics besides graphical methods?
  2. How does the vertex form of a quadratic equation relate to its graph?
  3. How do you determine whether a parabola opens upwards or downwards?
  4. What is the significance of the discriminant in quadratic equations?
  5. Can all quadratic equations be factored easily?

Tip: To confirm the accuracy of a graph, always verify the roots algebraically.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Graphing Parabolas

Formulas

Factoring: (x - 4)(x + 3) = 0
Vertex formula: x = -b/2a

Theorems

Factoring of Quadratic Equations
Vertex Theorem for Parabolas

Suitable Grade Level

Grades 8-10