Here's the breakdown:

* Zeros of a function: These are the x-values (or the input values) where the function's output (or y-value) is equal to zero. In other words, it's where the graph of the function crosses the x-axis.

* Definition: A function is defined at a point if it has a specific output value for that input.

Putting it together:

Yes, a function is considered defined at a point where it's equal to zero. The function simply has a value of zero at that specific input.

Example:

Consider the function f(x) = x² - 4. This function is equal to zero when x = 2 and x = -2.

* f(2) = 2² - 4 = 0

* f(-2) = (-2)² - 4 = 0

The function is defined at these points because it has a specific output (zero) for each input.

Important note: Sometimes a function might not be defined at a point even if it's equal to zero. This typically happens when the function has a "hole" or a vertical asymptote at that point. For example, the function f(x) = (x² - 4)/(x - 2) is undefined at x = 2, even though f(2) = 0 if we ignore the hole.