Math Problem Statement

Consider the function f(x) = 3x^2 - 24x - 4. Determine, without graphing, whether the function has a minimum value or a maximum value. Find the minimum or maximum value and determine where it occurs. Identify the function's domain and its range.

Solution

Let's analyze the function f(x)=3x224x4f(x) = 3x^2 - 24x - 4, as requested in the image.

Part a: Determine if the function has a minimum or maximum value.

This is a quadratic function of the form f(x)=ax2+bx+cf(x) = ax^2 + bx + c, where a=3a = 3, b=24b = -24, and c=4c = -4.

For a quadratic function:

  • If a>0a > 0, the parabola opens upwards and the function has a minimum value.
  • If a<0a < 0, the parabola opens downwards and the function has a maximum value.

Since a=3>0a = 3 > 0, the function has a minimum value.

Part b: Find the minimum value and determine where it occurs.

To find the minimum value, we first need to find the vertex of the parabola, which occurs at x=b2ax = \frac{-b}{2a}.

x=(24)2(3)=246=4x = \frac{-(-24)}{2(3)} = \frac{24}{6} = 4

Now, substitute x=4x = 4 back into the function to find the minimum value:

f(4)=3(4)224(4)4=3(16)964=48964=52f(4) = 3(4)^2 - 24(4) - 4 = 3(16) - 96 - 4 = 48 - 96 - 4 = -52

Thus, the minimum value is 52-52, and it occurs at x=4x = 4.

Part c: Identify the function's domain and range.

  • The domain of a quadratic function is all real numbers, i.e., (,)(-\infty, \infty).
  • The range depends on the vertex and the direction of the parabola:
    • Since the parabola opens upwards (because a>0a > 0), the range starts from the minimum value 52-52 and goes to infinity.
    • Therefore, the range is [52,)[-52, \infty).

Summary:

  • a. The function has a minimum value.
  • b. The minimum value is 52-52 at x=4x = 4.
  • c. Domain: (,)(-\infty, \infty), Range: [52,)[-52, \infty).

Would you like further details or explanations?

Here are 5 related questions you might find useful:

  1. How do you determine the vertex of any quadratic function?
  2. What happens when the leading coefficient aa is negative in a quadratic function?
  3. How do you find the axis of symmetry for a quadratic equation?
  4. Can quadratic functions have both a minimum and maximum value?
  5. How do transformations affect the graph of a quadratic function?

Tip: Remember, the sign of the leading coefficient aa determines whether a quadratic function has a minimum or maximum!

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Domain and Range

Formulas

General quadratic form: f(x) = ax^2 + bx + c
Vertex formula: x = -b/(2a)

Theorems

The parabola opens upwards if a > 0 (minimum value), and downwards if a < 0 (maximum value)

Suitable Grade Level

Grades 9-12