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3.6-2 Composing, Decomposing Functions • Recall from yesterday, we can make a combination of functions through using the basic operations – +, -, /, x • Now, we can compose a new function by essentially “embedding” one function into another Composition • Composition = the composition of a function f and g, denoted as f o g , is defined as f(g(x)) – Read as “f of g,” or “fog” – Not the same as g(f(x)) • Just like yesterday, we can evaluate as a point, OR as a new function with a new defined domain • After we compose a function, we can then use it evaluate new function values • (f ○ g)(x) is the new function • (f ○ g)(5) means to replace every x, in the composed function, with a 5 • Example. If f(x) = 2x – 3, and g(x) = x + 5, find: • A) (f ○ g)(6) • B) (f ○ g)(x) • Example. If f(x) = x2 + 2, and g(x) = x, find the formulas and state the domains for: • A) (f ○ g)(x) • B) (g ○ f)(x) Decomposition • On the other hand, we can decompose = break down a function into simpler/separate functions • Best to work “inside-out” • Look at the argument, and determine what the function is doing to the argument – Portion inside the main function • Example. Decompose the function f(x) = (x4 + 1)3 into two functions. • What is inside the argument? • What is on the outside? • Example. Decompose the function f(x) = 3 3 x 2 1 into two functions. And, three functions. • • • • Assignment Pg. 270 #31-65 odd Just find the formulas for fog on 41-53.