Math Problem Statement

Determine the domains and variation tables of the functions f(x) = -x^2 + 2x - 2, g(x) = (-2x - 6) / (2x + 1), and h(x) = sqrt(x - 2). Calculate specific values for these functions over given intervals.

Solution

Let’s solve the problem step by step based on the uploaded image.

Given Functions:

  1. f(x)=x2+2x2f(x) = -x^2 + 2x - 2
  2. g(x)=2x62x+1g(x) = \frac{-2x - 6}{2x + 1}
  3. h(x)=x2h(x) = \sqrt{x - 2}

Questions:

  1. Determine DfD_f, DgD_g, DhD_h (domains of ff, gg, and hh).
  2. (a) Create the variation tables for ff, gg, and hh.
    (b) Calculate specific values:
    • h([3,6])h([3,6])
    • g([2,1])g([-2,-1])
    • f([1,3])f([-1,3]).

Step 1: Domains

  1. Domain of f(x)=x2+2x2f(x) = -x^2 + 2x - 2: f(x)f(x) is a quadratic polynomial, so it is defined for all xRx \in \mathbb{R}.
    Df=R\boxed{D_f = \mathbb{R}}.

  2. Domain of g(x)=2x62x+1g(x) = \frac{-2x - 6}{2x + 1}: The denominator must not be zero: 2x+10    x12.2x + 1 \neq 0 \implies x \neq -\frac{1}{2}. Hence,
    Dg=R{12}\boxed{D_g = \mathbb{R} \setminus \{-\frac{1}{2}\}}.

  3. Domain of h(x)=x2h(x) = \sqrt{x - 2}: The expression inside the square root must be non-negative: x20    x2.x - 2 \geq 0 \implies x \geq 2. Hence,
    Dh=[2,)\boxed{D_h = [2, \infty)}.


Step 2: Variation Tables

(a) Behavior of the Functions

  1. Variation Table for f(x)f(x):

    • f(x)=x2+2x2f(x) = -x^2 + 2x - 2 is a quadratic function.
    • Rewrite in vertex form: f(x)=(x22x)2=(x1)2+12=(x1)21.f(x) = -(x^2 - 2x) - 2 = -(x - 1)^2 + 1 - 2 = -(x - 1)^2 - 1.
    • Vertex: (1,1)(1, -1). Since the coefficient of x2x^2 is negative, the parabola opens downward.
    • Critical points:
      • f(x)f(x) increases on (,1](-\infty, 1] and decreases on [1,)[1, \infty).
  2. Variation Table for g(x)g(x):

    • g(x)=2x62x+1g(x) = \frac{-2x - 6}{2x + 1}.
    • Vertical asymptote: x=12x = -\frac{1}{2}.
    • Horizontal asymptote: As x±x \to \pm\infty, g(x)1g(x) \to -1 (degree of numerator = degree of denominator).
  3. Variation Table for h(x)h(x):

    • h(x)=x2h(x) = \sqrt{x - 2} is defined for x2x \geq 2.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Rational Functions
Square Root Functions
Domain and Range
Variation Tables

Formulas

Quadratic function: f(x) = ax^2 + bx + c
Rational function: g(x) = P(x)/Q(x)
Square root function: h(x) = sqrt(x - c)

Theorems

Vertex form of a quadratic function
Domain restrictions for rational and square root functions

Suitable Grade Level

Grades 9-12