Math Problem Statement

Suppose that the x-intercepts of the graph of y = f(x) are -5 and 3. What are the x-intercepts of the graphs of the transformed functions y = f(x + 6), y = f(x - 8), y = 2f(x), and y = f(-x)?

Solution

Let's work through this problem step by step. The x-intercepts of the graph of y=f(x)y = f(x) are given as 5-5 and 33. This means that f(5)=0f(-5) = 0 and f(3)=0f(3) = 0, which are the points where the graph crosses the x-axis.

We will now answer the given questions based on transformations of f(x)f(x).

(a) What are the x-intercepts of the graph of y=f(x+6)y = f(x + 6)?

  • The transformation f(x+6)f(x + 6) represents a horizontal shift to the left by 6 units.
  • The original x-intercepts are at 5-5 and 33. After shifting left by 6, the new intercepts are: 56=11and36=3.-5 - 6 = -11 \quad \text{and} \quad 3 - 6 = -3. Answer: The x-intercepts are 11-11 and 3-3.

(b) What are the x-intercepts of the graph of y=f(x8)y = f(x - 8)?

  • The transformation f(x8)f(x - 8) represents a horizontal shift to the right by 8 units.
  • The original x-intercepts are at 5-5 and 33. After shifting right by 8, the new intercepts are: 5+8=3and3+8=11.-5 + 8 = 3 \quad \text{and} \quad 3 + 8 = 11. Answer: The x-intercepts are 33 and 1111.

(c) What are the x-intercepts of the graph of y=2f(x)y = 2f(x)?

  • The transformation 2f(x)2f(x) represents a vertical stretch by a factor of 2.
  • A vertical stretch does not change the x-intercepts, as the graph is only stretched vertically, leaving the points where f(x)=0f(x) = 0 unchanged. The x-intercepts remain the same at 5 and 3.\text{The x-intercepts remain the same at } -5 \text{ and } 3. Answer: The x-intercepts are 5-5 and 33.

(d) What are the x-intercepts of the graph of y=f(x)y = f(-x)?

  • The transformation f(x)f(-x) represents a reflection over the y-axis.
  • To find the new x-intercepts, we reflect the original x-intercepts 5-5 and 33 over the y-axis. This means we take the opposite signs: (5)=5and(3)=3.-(-5) = 5 \quad \text{and} \quad -(3) = -3. Answer: The x-intercepts are 55 and 3-3.

Would you like further clarification or additional details? Here are some related questions:

  1. How does the transformation y=f(kx)y = f(kx) affect the graph's x-intercepts?
  2. Can you explain how vertical and horizontal transformations differ?
  3. What happens to the x-intercepts if we apply a transformation like y=f(x)+ky = f(x) + k?
  4. How do reflections over the x-axis affect the x-intercepts of a function?
  5. If a graph is shifted both vertically and horizontally, how do we determine the new x-intercepts?

Tip: When working with function transformations, remember that horizontal shifts affect the x-values, while vertical shifts affect the y-values.

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Math Problem Analysis

Mathematical Concepts

Function Transformations
Horizontal Shifts
Vertical Stretch
Reflection

Formulas

x-intercepts shift horizontally: f(x ± c)
Reflection over the y-axis: f(-x)
Vertical stretch: af(x)

Theorems

Transformation Theorem
Reflection Theorem

Suitable Grade Level

Grades 9-12