Algebra 2: Section 7.4 Inverse Functions
Inverse Relation Maps the output back to original input Domain of inverse is the range of the original function
Finding Inverse of a Function (Algebraically) Rewrite function name; usually f(x) as y Switch the x’s and y’s Solve for y
Finding Inverse of a Function
Power Function A function of the form Where a is a real number b is rational
Finding Inverse of a Function
Finding Inverse of a Function
Verifying Functions are Inverses Functions are inverses of each other if… f(g(x)) = x AND g(f(x)) = x f -1(x) = g(x) Reads “inverse of f”
Verify that f and g are inverses f and g are inverses of each other!!!
Homework P.426 #16-24 all #25-31 odd
Inverse Functions (Day 2) Algebra 2: Section 7.4 Inverse Functions (Day 2)
Warm-Up What is the range of a function? Output values y-values What is the domain of a function? Input values x-values
Finding Inverses of a Function (Graphically) To create the inverse graph of a function… Reflect the original graph across the line y = x. Examples on Board!!! Swap x and y values of plotted points y = x2 y = x3 Sketchpad Example
Warm-Up Write the image of each point after its reflection in the line y = x. (2, 3) (-2, 4) (-1, -1) (1, -3)
Inverse Functions An inverse relation may or may not be a function (even if the original IS a function!) Graph original in calculator (y1) Graph inverse in calculator (y2) Is the inverse a function? How could you tell by looking at only the graph of the original function?
Horizontal Line Test Look at original function If no horizontal line intersects the graph of the function more than once, then the inverse of the original will also be a function So, if a relation passes the vertical and horizontal line tests then the original relation and its inverse are functions Vertical Line Test original function Horizontal Line Test inverse function
Examples: Find the inverse
Homework P.427 #36-56 all Use graphing calculator for #48-56 Draw sketch of graph on homework
Verifying if Functions are Inverses Using TI-83 Enter each function into Y1 and Y2 Enter Y1(Y2) into Y3 Enter Y2(Y1) into Y4 Turn on graph of Y3 only See if it is the graph of y=x Turn on graph of Y4 only Verify #31, p.426 using TI-83