## Precalculus (6th Edition)

See p.408, Tests to Determine Whether a Function Is One-to-One 1. Show that $f(a)=f(b)$ implies $a=b$. This means that $f$ is one-to-one. ----------- $y=f(x)=2x-8$ Assume that $f(a)=f(b)$ $\ \ \Rightarrow \ \ 2a-8=2b-8\qquad /+8$ $\ \ \Rightarrow \ \ 2a=2b\qquad /\div 2$ $\ \ \Rightarrow \ \ a=b$ $f$ is one-to-one