Math Problem Statement

Consider the function f(x) = -3x^2 + 6x - 8. 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

The function given in the image is f(x)=3x2+6x8f(x) = -3x^2 + 6x - 8.

Part (a)

To determine if the function has a minimum or maximum value, we look at the coefficient of x2x^2 in the quadratic function f(x)=ax2+bx+cf(x) = ax^2 + bx + c.

  • If a>0a > 0, the parabola opens upward, and the function has a minimum.
  • If a<0a < 0, the parabola opens downward, and the function has a maximum.

In this case, a=3a = -3, which is less than 0, so the function has a maximum value.

Part (b)

To find the maximum value and where it occurs, we use the vertex formula: x=b2ax = \frac{-b}{2a} Here, a=3a = -3 and b=6b = 6. Substituting these values into the formula: x=62(3)=1x = \frac{-6}{2(-3)} = 1

Now substitute x=1x = 1 back into the function f(x)f(x) to find the maximum value: f(1)=3(1)2+6(1)8=3+68=5f(1) = -3(1)^2 + 6(1) - 8 = -3 + 6 - 8 = -5 So, the maximum value is 5-5, and it occurs at x=1x = 1.

Part (c)

  • The domain of any quadratic function is all real numbers: (,)(-\infty, \infty).
  • The range of the function depends on the maximum value. Since the maximum value is 5-5, the range is (,5](-\infty, -5].

Summary:

  • (a) The function has a maximum value.
  • (b) The maximum value is 5-5, and it occurs at x=1x = 1.
  • (c) The domain is (,)(-\infty, \infty), and the range is (,5](-\infty, -5].

Would you like further details on any part of the solution?


Here are 5 related questions:

  1. How do you determine the vertex of a quadratic function?
  2. What does the sign of the leading coefficient in a quadratic equation tell you about its graph?
  3. Can a quadratic function have both a minimum and a maximum value?
  4. How do you find the axis of symmetry for a quadratic function?
  5. What is the general form of a quadratic equation?

Tip: Always check the sign of the x2x^2 coefficient to know if a quadratic function has a minimum or maximum.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Algebra
Parabolas
Domain and Range

Formulas

Vertex formula: x = -b / 2a
Quadratic function form: ax^2 + bx + c

Theorems

Properties of parabolas (upward/downward direction based on the leading coefficient)

Suitable Grade Level

Grades 9-10