Math Problem Statement

Find the range and domain of the function f(x) = -4x^2 + 3x - 3.

Solution

The problem is asking for the domain and range of the quadratic function:

f(x)=4x2+3x3f(x) = -4x^2 + 3x - 3

1. Domain:

The domain of a quadratic function is all real numbers, because it is defined for any input xx. There's no restriction on xx like division by zero or square roots of negative numbers that would limit the domain.

Thus, the domain is: R(All real numbers)\mathbb{R} \quad \text{(All real numbers)}

2. Range:

For the range, we need to determine the possible output values of the function. Since the coefficient of x2x^2 is negative (4-4), the parabola opens downward. The function has a maximum value, and we can find that maximum using the vertex formula.

Step 1: Find the vertex

The xx-coordinate of the vertex for a quadratic function ax2+bx+cax^2 + bx + c is given by: x=b2ax = \frac{-b}{2a} For the function f(x)=4x2+3x3f(x) = -4x^2 + 3x - 3, we have:

  • a=4a = -4
  • b=3b = 3

Substitute these values: x=32(4)=38=38x = \frac{-3}{2(-4)} = \frac{-3}{-8} = \frac{3}{8}

Step 2: Find the maximum value by substituting the xx-coordinate of the vertex back into the function

f(38)=4(38)2+3(38)3f\left(\frac{3}{8}\right) = -4\left(\frac{3}{8}\right)^2 + 3\left(\frac{3}{8}\right) - 3

First, calculate (38)2\left(\frac{3}{8}\right)^2: (38)2=964\left(\frac{3}{8}\right)^2 = \frac{9}{64}

Now substitute into the function:

= -\frac{36}{64} + \frac{9}{8} - 3 = -\frac{9}{16} + \frac{9}{8} - 3$$ Convert $$\frac{9}{8}$$ to have a denominator of 16: $$\frac{9}{8} = \frac{18}{16}$$ Now substitute: $$f\left(\frac{3}{8}\right) = -\frac{9}{16} + \frac{18}{16} - 3 = \frac{9}{16} - 3$$ Convert $$-3$$ to have a denominator of 16: $$-3 = \frac{-48}{16}$$ Now, add the fractions: $$f\left(\frac{3}{8}\right) = \frac{9}{16} - \frac{48}{16} = \frac{-39}{16}$$ Thus, the maximum value of $$f(x)$$ is $$\frac{-39}{16}$$. ### 3. **Range:** Since the parabola opens downward, the function's values go from $$-\infty$$ up to the maximum value of $$\frac{-39}{16}$$. Thus, the **range** is: $$(-\infty, \frac{-39}{16}]$$ --- Let me know if you'd like further details! Here are 5 additional questions related to this concept: 1. How do you determine the axis of symmetry for a quadratic function? 2. What does the sign of the leading coefficient of a quadratic function tell you about the graph? 3. How can you find the roots of the quadratic function $$f(x) = -4x^2 + 3x - 3$$? 4. How is the vertex form of a quadratic function related to its standard form? 5. What role does the discriminant play in analyzing the number of roots for a quadratic equation? **Tip:** When graphing a quadratic function, always check if it opens upwards (positive leading coefficient) or downwards (negative leading coefficient) to determine if it has a maximum or minimum point.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Domain
Range
Vertex

Formulas

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

Theorems

The range of a quadratic function depends on the vertex when the parabola opens upward or downward.

Suitable Grade Level

High School - College Algebra