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Dive into the fundamentals of inverse functions in mathematics with this comprehensive guide. Learn about the key principles, including the rule for reflection over the line y = x and how to find inverse functions both graphically and algebraically. We’ll explore function notation, switching x and y values, and the impact of limited ranges on domain. Practice problems are provided to reinforce your understanding, along with classwork and exit ticket discussions to enhance learning. Discover how to determine the inverse function effectively!
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Bell Ringer What do you think “inverse” means? What is the rule for reflection over the line y = x? Find the “sin” button on your calculator. What is written above it?
Inverse Functions Thursday, March 13, 2014
The Basics The inverse of a function is when you switch the x and y values. The graph of inverse functions is a reflection over the line y = x. Inverse function notation is f -1(x).
Ex: Switching x and y Find the inverse of the given function: f = {(1,2), (3,5), (-2,-5), (-7, 4)} The inverse is: f -1 = {(2,1), (5,3), (-5,-2), (4, -7)}
Finding the Inverse Algebraically (See Graphic Organizer) Switch to the y = notation from the f(x) =. Exchange x and y in the problem and solve for y. Rewrite as f -1(x).
Ex: Solving Algebraicallyf(x) = 3x2 - 8 • Switch notation • Switch x & y and solve for y • Add 8 to both sides • Divide both sides by 3 • Take the square root • Rewrite in function notation • y = 3x2 – 8 • x = 3y2 – 8 • x + 8 = 3y2 • x + 8 = y2 3 √ (x + 8) = y 3 f -1(x) = ± √ (x + 8) 3
Ex: Solving Algebraically • f(x) = √x • y = √x • x = √y • x2 = y • f -1 (x) = x2 • Copy • Rewrite in y = form • Switch x and y & solve for y • Square both sides • Write in function notation
Limits If a function has a limited range, then the domain of its inverse is limited.
Ex: Limits f(x) = √x The range of this function is y ≥ 0 This means the inverse function has a limited domain of x ≥ 0 So, f -1(x) = x2, x ≥ 0
Practice Problems Classwork – Worksheet 7.4 Inverse Functions Homework – Practice Problems (25)
Exit Ticket What are the 3 ways to determine the inverse of a function? Which way do you find easiest? Explain.