Composition of Functions Lesson 8.1
Introduction Value fed to first function Resulting value fed to second function End result taken from second function
Introduction Notation for composition of functions: Alternate notation:
Try It Out Given two functions: p(x) = 2x + 1 q(x) = x Then p ( q(x) ) = p (x 2 - 3) = 2 (x 2 - 3) + 1 = 2x Try determining q ( p(x) )
Try It Out q ( p(x) ) = q ( 2x + 1) = (2x + 1) 2 – 3 = 4x 2 + 4x + 1 – 3 = 4x 2 + 4x - 2
Using the Calculator Given Define these functions on your calculator
Using the Calculator Now try the following compositions: g( f(7) ) f( g(3) ) g( f(2) ) f( g(t) ) g( f(s) ) WHY ??
Using the Calculator Is it also possible to have a composition of the same function? g( g(3.5) ) = ???
Composition Using Graphs k(x) defined by the graphj(x) defined by the graph Do the composition of k( j(x) )
Composition Using Graphs It is easier to see what the function is doing if we look at the values of k(x), j(x), and then k( j(x) ) in tables:
Composition Using Graphs Results of k( j(x) )
Composition With Tables Consider the following tables of values: x12347 f(x)31427 g(x)72143 f(g(x)f(g(1)) g(f(x)g(f(3))
Decomposition of Functions Someone once dug up Beethoven's tomb and found him at a table busily erasing stacks of papers with music writing on them. They asked him... "What are you doing down here in your grave?" He responded, "I'm de-composing!!" But, seriously folks... Consider the following function which could be a composition of two different functions.
Decomposition of Functions The function could be decomposed into two functions, k and j
Assignment Lesson 8.1 Page 359 Exercises 1 – 59 odd