Chapter 3: Problem 75
Suppose that the function \(y=f(x)\) is increasing on the interval [-1,5] (a) Over what interval is the graph of \(y=f(x+2)\) increasing? (b) Over what interval is the graph of \(y=f(x-5)\) increasing? (c) Is the graph of \(y=-f(x)\) increasing, decreasing, or neither on the interval [-1,5]\(?\) (d) Is the graph of \(y=f(-x)\) increasing, decreasing, or neither on the interval [-5,1]\(?\)
Short Answer
Step by step solution
- Analyze the given function for part (a)
- Determine the interval for part (a)
- Analyze the given function for part (b)
- Determine the interval for part (b)
- Analyze the graph transformation for part (c)
- Determine the behavior for part (c)
- Analyze the graph transformation for part (d)
- Determine the behavior for part (d)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Transformations
The exercise explores the transformations involving horizontal shifts and reflections:
- Shifting the function horizontally affects the x-values. For instance, with an equation like y = f(x + 2), every point on the graph of y = f(x) is shifted left by 2 units.
- Reflections involve flipping the graph across an axis. For example, y = -f(x) reflects the graph of y = f(x) across the x-axis, while y = f(-x) reflects it across the y-axis.
Increasing and Decreasing Functions
For example, given that y = f(x) is increasing on the interval [-1, 5], this suggests:
- As x moves from -1 to 5, the value of f(x) continually increases.
- In part (c) of the exercise, y = -f(x) becomes decreasing because negating an increasing function flips its values. Therefore, on interval [-1, 5], y = -f(x) decreases.
Intervals of Functions
Here’s how intervals were used in the exercise:
- In part (a), for y = f(x + 2), each point in interval [-1, 5] shifts left by 2 units, resulting in a new interval [-3, 3].
- In part (b), for y = f(x - 5), every point in interval [-1, 5] shifts right by 5 units, resulting in the new interval [4, 10].
- Part (d) involves reflection, thus, the interval [-5, 1] is considered due to the reflection's effect.
Graph Behavior
In the exercise:
- Part (a) required analyzing behavior by shifting the graph horizontally to check where it increases.
- Part (b) involved determining the effect of a horizontal shift on the interval’s endpoints to see where the function increases.
- Part (c) considered the behavior change when negating the function, turning an increasing function into a decreasing one.
- Part (d) analyzed how reflecting the function across the y-axis affects its increasing nature, leading it to decrease where it initially increased.