1. Let's start by understanding what a one-to-one function is. A function $f$ is one-to-one (or injective) if for every $a$ and $b$ in the domain, whenever $f(a) = f(b)$, it implies that $a = b$. 2. To create a math problem involving one-to-one functions, we can ask to determine if a given function is one-to-one or not. 3. Example problem: Determine if the function $f(x) = 2x + 3$ is one-to-one. 4. To check if $f(x)$ is one-to-one, assume $f(a) = f(b)$: $$2a + 3 = 2b + 3$$ 5. Subtract 3 from both sides: $$2a = 2b$$ 6. Divide both sides by 2: $$a = b$$ 7. Since $a = b$ whenever $f(a) = f(b)$, the function $f(x) = 2x + 3$ is one-to-one. 8. Therefore, the function passes the horizontal line test and is injective. Final answer: $f(x) = 2x + 3$ is a one-to-one function.