Consider two functions f(x) and g(x).
Definition: Composition is the application of one function to the output of another.
Notation: fog(x)=f(g(x))
1. Function g processes input x.
2. Resulting value g(x) becomes the input for outer function f.
Example: What is f(g(x)) if f(x)=$$x^2+5$$ and g(x)=2x+3.
Sol. g(x)=2x+3
f(g(x))=f(2x+3)=$$(2x+3)^2+5$$=$$4x^2+12x+14$$
