Functions — Composition, Inverses & Symmetry
Big idea: functions are machines you can chain and reverse — composition feeds one into another, and an inverse undoes the work, reflected across \(y=x\).
Topics
Composition of Functions — \((f\circ g)(x)=f(g(x))\), domain of a composite, and decomposing a function into a chain.
Inverse Functions — the one-to-one test, finding \(f^{-1}\), and the reflection across \(y=x\).
Symmetry — even (\(f(-x)=f(x)\)) and odd (\(f(-x)=-f(x)\)) functions and their graphs.
You'll be able to…
- Evaluate and simplify \((f\circ g)(x)\) and state the domain of the composite.
- Determine whether a function is one-to-one and find its inverse algebraically.
- Classify a function as even, odd, or neither from its rule or graph.
- Verify that two functions are inverses using composition.
Worked example
Check: \(f\!\left(f^{-1}(x)\right)=2\!\left(\dfrac{x+6}{2}\right)-6\). \[ = (x+6)-6 = x \;\checkmark \]