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Chapter 3: Transformations of Graphs and Data. Lesson 5: The Graph Scale-Change Theorem Mrs. Parziale. Vocabulary:. Vertical stretch : A scale change that makes the original graph taller or shorter Horizontal stretch : a scale change that makes the original graph wider or skinnier.
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Chapter 3: Transformations of Graphs and Data Lesson 5: The Graph Scale-Change Theorem Mrs. Parziale
Vocabulary: • Vertical stretch:A scale change that makes the original graph taller or shorter • Horizontal stretch:a scale change that makes the original graph wider or skinnier. • Scale change:a stretch or shrink applied to the graph vertically or horizontally • Vertical scale change: The value that changes the vertical values of the graph. • Horizontal scale change:The value that changes the horizontal values of the graph. • Size change:When the same vertical and horizontal scale change occurs.
Example 1: Consider the graph of (a) Complete the table and graph on the grid:
(b) Replace (y) with . 1. Solve the new equation for y and graph it on the same grid at right. 2. What happens to the y-coordinates? 3. This is called a vertical stretch of magnitude 3 . 4. Under what scale change is the new figure a vertical scale change of the original?
(c) Replace (x) with . 1. Solve the new equation for y and graph it. 2. What happens to the x-coordinates? • This is called a horizontal stretch of magnitude 2 . • Under what scale change is the new figure a horizontal scale change of the original?
(d) Let . Find an equation for g(x), the image of f(x) under What is happening to each part of the graph?
How is the x changed? • Change: horizontal stretch two times wider. • How is the y changed? • Change: vertical stretch three times the original.
Graph Scale-Change Theorem In a relation described by a sentence in (x) and (y), the following two processes yield the same graph: (1) replace (x) by and (y) by in the sentence (2) apply the scale change __________________ to the graph of the original relation. Note: If a = b, then you have performed a __________ size change If a = negative, the graph has been reflected (flipped) over the y-axis If b = negative, the graph has been reflected over the x-axis
So, What’s the Equation? (d) Find an equation for g(x), the image of f(x) under
Example 2: • Consider . Find an equation for the function under • Describe what happens to all of the x values: • Describe what happens to all of the y values:
Find the equation for the transformed image by • Replace (x) with ______________ • Replace (y) with ______________ • Now make the new equation (remember to simplify to y= form):
Closure - Example 3: The graph to the right is y = f(x). Draw . • What should happen to all of the x values? • What should happen to all of the y values?