AP Precalculus / Unit 2: Exponential and Logarithmic Functions

2.7 Composition of Functions

3 practice questions

Notes

$(f\circ g)(x)=f(g(x))$: apply $g$ first, then $f$.

Order matters: usually $f(g(x))\ne g(f(x))$.
Domain: inputs where $g$ works and $g(x)$ is in $f$'s domain.

Practice

$f(x)=x^2$, $g(x)=x+1$. $f(g(2))=$

Using the same functions, $g(f(2))=$

$f(g(x))$ means:

Ready for more? Take the Unit 2 test.