Math Problem Statement

find domain and range for g(x)

Find the domain and range of g(x), where f(x) = sqrt(x), x in [0, 4], and g(x) = -2f(2x - 4) + 3.

Solution

To determine the domain and range of g(x)g(x), we will analyze the given definitions of f(x)f(x) and g(x)g(x):

  1. Definition of f(x)f(x): f(x)=x,x[0,4]f(x) = \sqrt{x}, \quad x \in [0, 4].

    • Domain of f(x)f(x): [0,4][0, 4] (since square roots require x0x \geq 0 and the interval is restricted to [0,4][0, 4]).
    • Range of f(x)f(x): [0,2][0, 2] (since 4=2\sqrt{4} = 2).
  2. Definition of g(x)g(x): g(x)=2f(2x4)+3g(x) = -2f(2x - 4) + 3.

    • For f(2x4)f(2x - 4) to be defined, we require: 2x4[0,4].2x - 4 \in [0, 4]. Solving this inequality: 02x44    42x8    2x4.0 \leq 2x - 4 \leq 4 \implies 4 \leq 2x \leq 8 \implies 2 \leq x \leq 4. Therefore, the domain of g(x)g(x) is [2,4][2, 4].

    • For the range of g(x)g(x):

      • When x[2,4]x \in [2, 4], 2x42x - 4 maps to [0,4][0, 4], which is the domain of f(x)f(x).
      • The output of f(x)f(x) is [0,2][0, 2], as established earlier.
      • Substituting into g(x)=2f(2x4)+3g(x) = -2f(2x - 4) + 3, we transform the range: y=2f(2x4)+3,f(2x4)[0,2].y = -2f(2x - 4) + 3, \quad f(2x - 4) \in [0, 2]. Let z=f(2x4)z = f(2x - 4), where z[0,2]z \in [0, 2]: g(x)=2z+3.g(x) = -2z + 3. For z=0z = 0, g(x)=2(0)+3=3g(x) = -2(0) + 3 = 3. For z=2z = 2, g(x)=2(2)+3=4+3=1g(x) = -2(2) + 3 = -4 + 3 = -1. Therefore, the range of g(x)g(x) is [1,3][-1, 3].

Final Answer:

  • Domain of g(x)g(x): [2,4][2, 4].
  • Range of g(x)g(x): [1,3][-1, 3].

Would you like further details or help with visualizing this function? Here are some related questions to deepen your understanding:

  1. How can we graph g(x)g(x) to confirm its domain and range?
  2. What transformations were applied to f(x)f(x) to create g(x)g(x)?
  3. How do we verify the range using algebraic bounds?
  4. Can we find any critical points of g(x)g(x) within its domain?
  5. What would happen to the domain and range if f(x)f(x) were defined on a different interval?

Tip: Always start by analyzing the inner function's domain before applying transformations to ensure accurate results.

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Math Problem Analysis

Mathematical Concepts

Functions
Domain and Range
Square Roots
Transformations of Functions

Formulas

f(x) = sqrt(x)
g(x) = -2f(2x - 4) + 3

Theorems

Properties of square root functions
Function transformations

Suitable Grade Level

Grades 10-12