Chapter 2: Problem 7
Suppose the graph of \(f\) is given. Describe how the graph of each function can be obtained from the graph of \(f\). (a) \(y=-f(x)\) (b) \(y=f(-x)\)
Short Answer
Expert verified
(a) Reflect over x-axis. (b) Reflect over y-axis.
Step by step solution
01
Understanding y = -f(x)
To transform the graph of a function to obtain the graph of \( y = -f(x) \), you need to reflect the original graph over the x-axis. This is because changing the sign of the entire function negates all the output values, flipping the graph upside down.
02
Reflecting over the x-axis
Take each point on the original graph, find its y-coordinate, and change its sign. If a point \((x, y)\) is on the graph of \( f(x) \), the corresponding point \((x, -y)\) will be on the graph of \( y = -f(x) \). Perform this transformation for all points on the graph.
03
Understanding y = f(-x)
For the transformation \( y = f(-x) \), reflect the original graph over the y-axis. This transformation affects the input values (x-coordinates) by negating them, which mirrors the graph horizontally across the y-axis.
04
Reflecting over the y-axis
To perform this reflection, take each point on the original graph, find its x-coordinate, and change its sign. A point \((x, y)\) on the graph of \( f(x) \) becomes \((-x, y)\) on the graph of \( y = f(-x) \). Apply this to all points on the original function graph.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reflection over the x-axis
When we talk about reflecting a graph over the x-axis, we are referring to flipping the graph upside down. Imagine taking each point on the graph and moving it to the other side of the x-axis. This kind of transformation is used to create the graph of \[y = -f(x)\]. Here, we change the sign of the output values of the function. That means, if you have a point \((x, y)\) on the original graph, after the transformation it turns into \((x, -y)\). In simpler terms, all the positive y-values become negative, and the negative y-values become positive.
- This transformation leaves the x-values unchanged.
- The effect is similar to "flipping over" so that what was above the x-axis is now below and vice versa.
Reflection over the y-axis
Reflecting over the y-axis is a horizontal transformation of the graph that mirrors it across the y-axis. In terms of function transformation, this type of reflection is expressed as \[y = f(-x)\]. Unlike the reflection over the x-axis, here we are flipping the graph from left to right.
- The x-coordinate of each point is negated, turning a point \((x, y)\) into \((-x, y)\).
- This means if a part of the graph extends to the right of the y-axis, after reflection, it extends to the left, maintaining the same distance from the y-axis.
Graph Transformations
Graph transformations are operations that alter the position or the shape of a graph of a function. They include a variety of modifications such as translations, reflections, stretches, and compressions.In terms of reflections:
- Reflection over the x-axis transforms \(f(x)\) to \(-f(x)\), flipping the graph vertically.
- Reflection over the y-axis transforms \(f(x)\) to \(f(-x)\), flipping the graph horizontally.