Final answer:
A one-to-one function, also known as an injective function, is a function where each element in the domain has a unique corresponding element in the range.
Step-by-step explanation:
A one-to-one function, also known as an injective function, is a function where each element in the domain has a unique corresponding element in the range. This means that no two different elements in the domain can map to the same element in the range.
To determine if a function is one-to-one, we can use the horizontal line test. If no horizontal line intersects the graph of the function more than once, then the function is one-to-one. Another way is to check if the function passes the vertical line test, which means that every vertical line intersects the graph of the function at most once.
For example, let's consider the function f(x) = x^2. This function is not one-to-one because different inputs, such as x = 2 and x = -2, would produce the same output, f(2) = 4 and f(-2) = 4.