Math Problem Statement

Find the roots by graphing: f(x)=-2x^2-4x-2

Solution

To find the roots of f(x)=2x24x2f(x) = -2x^2 - 4x - 2 by graphing, we need to identify where the parabola intersects the x-axis. The roots are the values of xx where f(x)=0f(x) = 0. Here's the process:

Steps:

  1. Graph the quadratic equation:

    • The function f(x)=2x24x2f(x) = -2x^2 - 4x - 2 is a downward-opening parabola (since the coefficient of x2x^2 is negative).
    • The vertex form or standard form of this equation provides a symmetrical parabola around its vertex.
  2. Find the vertex and axis of symmetry:

    • The axis of symmetry is x=b2ax = -\frac{b}{2a}, where a=2a = -2 and b=4b = -4. x=42(2)=1x = -\frac{-4}{2(-2)} = -1
    • The vertex occurs at x=1x = -1. Plugging this into the function: f(1)=2(1)24(1)2=2+42=0f(-1) = -2(-1)^2 - 4(-1) - 2 = -2 + 4 - 2 = 0 Thus, the vertex is (1,0)(-1, 0).
  3. Determine the roots:

    • Since the vertex lies on the x-axis, (1,0)(-1, 0) is also a root.
    • The parabola is symmetrical around the axis of symmetry, so there is no second root because the parabola touches the x-axis at a single point.

Roots:

The root of f(x)=2x24x2f(x) = -2x^2 - 4x - 2 is: x=1x = -1

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Math Problem Analysis

Mathematical Concepts

Graphing Quadratic Functions
Roots of Equations
Parabolas

Formulas

Axis of Symmetry Formula: x = -b / (2a)
Quadratic Equation: ax^2 + bx + c = 0

Theorems

The Vertex of a Parabola
Symmetry of Parabolas

Suitable Grade Level

Grades 9-11