To determine whether the function \( f(x) = 5x^5 - 3x \) is even, odd, or neither, we can use the definitions of even and odd functions:
- A function \( f(x) \) is even if \( f(-x) = f(x) \) for all \( x \).
- A function \( f(x) \) is odd if \( f(-x) = -f(x) \) for all \( x \).
Step 1: Calculate \( f(-x) \)
Let's find \( f(-x) \):
\[ f(-x) = 5(-x)^5 - 3(-x) \]
Calculating each term:
\[ (-x)^5 = -x^5 \quad \text{(since the exponent is odd)} \] \[ f(-x) = 5(-x^5) + 3x = -5x^5 + 3x \]
Step 2: Compare \( f(-x) \) with \( f(x) \)
- We know \( f(x) = 5x^5 - 3x \).
Now, let's check if \( f(-x) = f(x) \) (for even) or \( f(-x) = -f(x) \) (for odd):
-
Check for even function: \[ f(-x) = -5x^5 + 3x \quad \text{(not equal to \( 5x^5 - 3x \))} \]
-
Check for odd function: \[ -f(x) = -(5x^5 - 3x) = -5x^5 + 3x \] \[ f(-x) = -5x^5 + 3x \quad \text{(equal to \( -f(x) \))} \]
Conclusion
Since \( f(-x) = -f(x) \), the function \( f(x) = 5x^5 - 3x \) is an odd function.
Thus, the option that describes the function \( f(x) \) is:
Option 2: odd function.