An even function is a function $f(x)$ where $f(x) = f(-x)$ for all $x$ in its domain. This symmetry means the graph of an even function is mirrored across the y-axis.
5 Must Know Facts For Your Next Test
The graph of an even function is symmetric with respect to the y-axis.
If $f(x)$ is a polynomial, it is even if all powers of $x$ are even (e.g., $f(x) = x^2 + 4$).
Common examples of even functions include $f(x) = x^2$ and $f(x) = \cos(x)$.
The sum or difference of two even functions is also an even function.
A function can be neither even nor odd if it doesn't satisfy the conditions for either.