Math Problem Statement

Determine the opening of the graph of each quadratic function.

Solution

The problem asks to determine the direction of the opening of each quadratic function from the image. For quadratic functions, the key to determining whether the graph opens upwards or downwards is based on the coefficient of the x2x^2 term. Specifically:

  • If the coefficient of x2x^2 is positive, the parabola opens upward.
  • If the coefficient of x2x^2 is negative, the parabola opens downward.

Let’s analyze each equation in the image:

  1. y=(x+5)22y = (x + 5)^2 - 2

    • Expand the equation: y=(x+5)22=x2+10x+252=x2+10x+23y = (x + 5)^2 - 2 = x^2 + 10x + 25 - 2 = x^2 + 10x + 23.
    • The coefficient of x2x^2 is positive (1)(1), so the parabola opens upward.
  2. y=2x2+4x3y = -2x^2 + 4x - 3

    • The coefficient of x2x^2 is negative (2)(-2), so the parabola opens downward.
  3. y=(x+1)28y = -(x + 1)^2 - 8

    • Expand the equation: y=(x+1)28=(x2+2x+1)8=x22x9y = -(x + 1)^2 - 8 = -(x^2 + 2x + 1) - 8 = -x^2 - 2x - 9.
    • The coefficient of x2x^2 is negative (1)(-1), so the parabola opens downward.
  4. y=2x2+8x3y = 2x^2 + 8x - 3

    • The coefficient of x2x^2 is positive (2)(2), so the parabola opens upward.
  5. y=(x2)2+1y = (x - 2)^2 + 1

    • Expand the equation: y=(x2)2+1=x24x+4+1=x24x+5y = (x - 2)^2 + 1 = x^2 - 4x + 4 + 1 = x^2 - 4x + 5.
    • The coefficient of x2x^2 is positive (1)(1), so the parabola opens upward.

Summary of Openings:

  1. y=(x+5)22y = (x + 5)^2 - 2: Upward
  2. y=2x2+4x3y = -2x^2 + 4x - 3: Downward
  3. y=(x+1)28y = -(x + 1)^2 - 8: Downward
  4. y=2x2+8x3y = 2x^2 + 8x - 3: Upward
  5. y=(x2)2+1y = (x - 2)^2 + 1: Upward

Let me know if you'd like further details or explanations!


Here are five follow-up questions:

  1. How do you determine the vertex of a quadratic function in vertex form?
  2. Can you convert a quadratic function from standard form to vertex form?
  3. How does the axis of symmetry relate to the vertex in these equations?
  4. What impact does the constant term have on the graph of a quadratic function?
  5. Can a parabola that opens downward have a minimum point?

Tip: In vertex form y=a(xh)2+ky = a(x - h)^2 + k, the sign of aa determines the direction of the parabola's opening!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Graphing Parabolas

Formulas

Quadratic formula: y = ax^2 + bx + c
Vertex form: y = a(x - h)^2 + k

Theorems

Parabola opening direction theorem

Suitable Grade Level

Grades 9-11