You can tell if a function is even or odd by looking at its graph and how it shows symmetry:
Even Functions
- What It Means: A function called f(x) is even if changing the sign of x doesn’t change the value of the function. In simpler terms, f(−x)=f(x) for every x.
- Symmetry: The graphs of even functions look the same on both sides of the y-axis (the vertical line in the middle).
- Example: A good example is the graph of f(x)=x2. It is symmetrical around the y-axis.
Odd Functions
- What It Means: A function f(x) is odd if changing the sign of x flips the sign of the function’s value. So, we have f(−x)=−f(x) for all x.
- Symmetry: The graphs of odd functions have a symmetry around the origin (the point where the x and y axes cross).
- Example: The graph of f(x)=x3 shows this kind of symmetry.
By looking at these features, you can quickly tell whether a function is even or odd!