Math Problem Statement

For f(x) = log3 (x+3)-4 a) sketch the graph using transformations. Label any asymptotes with their equations, start by naming and stating the parent function, show at least 4 points on each graph. b) Find the domain of f(x). c) find the range of f(x).

Solution

Let's work through the problem step-by-step.

Part (a): Sketch the Graph Using Transformations

  1. Identify the Parent Function:
    The parent function is f(x)=log3(x)f(x) = \log_3(x).

    The basic characteristics of f(x)=log3(x)f(x) = \log_3(x) are:

    • Asymptote: x=0x = 0
    • Domain: x>0x > 0
    • Range: (,)(-\infty, \infty)
    • A few key points are (1,0)(1, 0), (3,1)(3, 1), (13,1)\left( \frac{1}{3}, -1 \right).
  2. Transformations of the Function f(x)=log3(x+3)4f(x) = \log_3(x+3) - 4:

    • Horizontal Shift: The x+3x + 3 inside the logarithm shifts the graph left by 3 units.
    • Vertical Shift: The 4-4 outside the logarithm shifts the graph down by 4 units.
  3. Applying the Transformations:

    • New Asymptote: The horizontal shift of 3 units to the left moves the asymptote from x=0x = 0 to x=3x = -3. So, the asymptote for this function is: x=3x = -3

    • Plot Key Points:

      • Start with the points of the parent function and apply the transformations to them:
        • Original Point (1, 0): Shift left by 3 units and down by 4 units to get (2,4)(-2, -4).
        • Original Point (3, 1): Shift left by 3 units and down by 4 units to get (0,3)(0, -3).
        • Original Point (13,1)\left( \frac{1}{3}, -1 \right): Shift left by 3 units and down by 4 units to get (83,5)\left( -\frac{8}{3}, -5 \right).
        • Choose one additional point, such as:
          • Original Point (9,2)\left(9, 2 \right): Shift left by 3 units and down by 4 units to get (6,2)\left(6, -2\right).
  4. Graph Sketch:

    • Plot these transformed points: (2,4)(-2, -4), (0,3)(0, -3), (83,5)\left( -\frac{8}{3}, -5 \right), and (6,2)(6, -2).
    • Draw the vertical asymptote at x=3x = -3.
    • Use these points to sketch the curve approaching the asymptote at x=3x = -3 from the right, and moving upwards slowly as xx increases.

Part (b): Domain of f(x)f(x)

The domain is determined by the argument of the logarithmic function being positive: x+3>0x + 3 > 0 x>3x > -3 So, the domain of f(x)f(x) is: (3,)(-3, \infty)

Part (c): Range of f(x)f(x)

Since this function involves a vertical shift of the logarithmic function, which has an original range of (,)(-\infty, \infty), the range remains: (,)(-\infty, \infty)


Would you like more details on any of these steps, or have any questions? Here are some related questions that might interest you:

  1. What would happen if the function were f(x)=log3(x+3)+4f(x) = \log_3(x + 3) + 4?
  2. How would the transformations change if we used a base 10 logarithm instead?
  3. Can you determine the inverse function of f(x)=log3(x+3)4f(x) = \log_3(x + 3) - 4?
  4. How would a horizontal compression affect the graph of f(x)=log3(x)f(x) = \log_3(x)?
  5. What is the effect of changing the base from 3 to another number?

Tip: When graphing transformations, applying shifts systematically (horizontal first, then vertical) helps to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Functions
Transformations of Functions
Domain and Range

Formulas

f(x) = log_b(x + h) + k
Domain: x + h > 0
Range: (-∞, ∞) for log functions

Theorems

Transformation Theorem for Logarithmic Functions

Suitable Grade Level

Grades 10-12