Math Problem Statement

Use the quadratic function f(x) = x^2 - 4x - 12 to answer the following: a) Determine the vertex. b) Does the graph open up or open down? c) What is the equation of the axis of symmetry? d) Find any x-intercepts. e) Find the y-intercept. f) Sketch the graph. g) State the domain and range in interval notation.

Solution

Let's analyze and solve the problem based on the quadratic function provided:

f(x)=x24x12f(x) = x^2 - 4x - 12

a) Determine the vertex:

The formula to find the vertex of a parabola f(x)=ax2+bx+cf(x) = ax^2 + bx + c is given by: x=b2ax = -\frac{b}{2a} Here, a=1a = 1, b=4b = -4, and c=12c = -12. Let's calculate the x-coordinate of the vertex: x=42(1)=42=2x = -\frac{-4}{2(1)} = \frac{4}{2} = 2 To find the y-coordinate, substitute x=2x = 2 back into the equation for f(x)f(x): f(2)=(2)24(2)12=4812=16f(2) = (2)^2 - 4(2) - 12 = 4 - 8 - 12 = -16 So, the vertex is (2,16)(2, -16).

b) Does the graph "open up" or "open down"?

Since the coefficient of x2x^2 (i.e., a=1a = 1) is positive, the parabola opens upward.

c) What is the equation of the axis of symmetry?

The axis of symmetry is a vertical line that passes through the vertex. The equation is: x=2x = 2

d) Find any x-intercepts:

To find the x-intercepts, set f(x)=0f(x) = 0 and solve for xx: x24x12=0x^2 - 4x - 12 = 0 Using the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Substitute a=1a = 1, b=4b = -4, and c=12c = -12: x=(4)±(4)24(1)(12)2(1)=4±16+482=4±642=4±82x = \frac{-(-4) \pm \sqrt{(-4)^2 - 4(1)(-12)}}{2(1)} = \frac{4 \pm \sqrt{16 + 48}}{2} = \frac{4 \pm \sqrt{64}}{2} = \frac{4 \pm 8}{2} So, the solutions are: x=4+82=6andx=482=2x = \frac{4 + 8}{2} = 6 \quad \text{and} \quad x = \frac{4 - 8}{2} = -2 Thus, the x-intercepts are x=6x = 6 and x=2x = -2.

e) Find the y-intercept:

To find the y-intercept, substitute x=0x = 0 into the equation: f(0)=024(0)12=12f(0) = 0^2 - 4(0) - 12 = -12 So, the y-intercept is (0,12)(0, -12).

f) Sketch the graph:

The graph is a parabola opening upwards with the following key points:

  • Vertex at (2,16)(2, -16)
  • X-intercepts at (2,0)(-2, 0) and (6,0)(6, 0)
  • Y-intercept at (0,12)(0, -12)

g) State the domain and range in interval notation:

  • The domain of any quadratic function is all real numbers: (,)(-\infty, \infty).
  • The range is all values of yy greater than or equal to the minimum value (the y-coordinate of the vertex): [16,)[-16, \infty).

Do you want further clarification on any of these steps or a deeper explanation of any part?

Here are 5 related questions you might want to explore:

  1. How do you use the discriminant to determine the number of x-intercepts for a quadratic function?
  2. Can you explain the relationship between the vertex and the axis of symmetry?
  3. How does changing the value of aa affect the graph of a parabola?
  4. What is the significance of the y-intercept in graphing quadratic functions?
  5. How do you derive the quadratic formula?

Tip: Always check the sign of the leading coefficient aa to determine whether a parabola opens upward (positive) or downward (negative).

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Parabolas
Graphing
Intercepts

Formulas

Vertex formula: x = -b/(2a)
Quadratic formula: x = [-b ± sqrt(b² - 4ac)] / 2a

Theorems

Quadratic Formula Theorem
Vertex of a Parabola Theorem

Suitable Grade Level

Grades 9-10