Math Problem Statement

Sketch the graph of y = x^2 + 6x + 8. Clearly show the coordinates of any points of intersection with the axes.

Solution

To sketch the graph of the quadratic equation y=x2+6x+8y = x^2 + 6x + 8, let's analyze the equation and find its intercepts with the axes:

  1. Finding the y-intercept:

    • The y-intercept occurs when x=0x = 0.
    • Substitute x=0x = 0 into the equation: y=02+60+8=8y = 0^2 + 6 \cdot 0 + 8 = 8
    • So, the y-intercept is at (0,8)(0, 8).
  2. Finding the x-intercepts:

    • The x-intercepts occur when y=0y = 0.
    • Set the equation equal to zero: x2+6x+8=0x^2 + 6x + 8 = 0
    • Factor the quadratic expression: (x+4)(x+2)=0(x + 4)(x + 2) = 0
    • Solve for xx: x+4=0x=4x + 4 = 0 \Rightarrow x = -4 x+2=0x=2x + 2 = 0 \Rightarrow x = -2
    • So, the x-intercepts are at (4,0)(-4, 0) and (2,0)(-2, 0).
  3. Sketching the Graph:

    • The equation y=x2+6x+8y = x^2 + 6x + 8 represents a parabola that opens upward because the coefficient of x2x^2 is positive.
    • The vertex of the parabola can be found by using the formula x=b2ax = -\frac{b}{2a}: x=621=3x = -\frac{6}{2 \cdot 1} = -3
    • Substitute x=3x = -3 back into the equation to find the y-coordinate of the vertex: y=(3)2+6(3)+8=918+8=1y = (-3)^2 + 6 \cdot (-3) + 8 = 9 - 18 + 8 = -1
    • Thus, the vertex is at (3,1)(-3, -1).

With this information:

  • The y-intercept is at (0,8)(0, 8).
  • The x-intercepts are at (4,0)(-4, 0) and (2,0)(-2, 0).
  • The vertex is at (3,1)(-3, -1).

If you'd like, I can provide a sketch based on this analysis or further details on the steps taken.


Would you like a graph or further details?

Here are five questions to explore related concepts:

  1. How do we determine the direction in which a parabola opens?
  2. What is the significance of the vertex in the graph of a quadratic function?
  3. How can the discriminant help in identifying the number of x-intercepts?
  4. What changes if the quadratic equation has a negative leading coefficient?
  5. How does the axis of symmetry relate to the graph of a quadratic equation?

Tip: The vertex form of a quadratic function can be useful for identifying the vertex directly, making graphing easier.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Graphing

Formulas

y = ax^2 + bx + c (standard form of a quadratic function)
x-intercepts by factoring

Theorems

Intercepts of Quadratic Functions
Axis of Symmetry for Parabolas

Suitable Grade Level

Grades 9-11