Answer:
f(x) = -x is odd
Step-by-step explanation:
A function f is odd if f(-x) = -f(x) for all x in the domain of f. Then, let's check each of the functions.
1. f(x) = x^3 + 5x^2 + x
f(-x) = (-x)^3 + 5(-x)^2 + (-x) = -x^3 + 5x^2 - x
-f(x) = -(x^3 + 5x^2 + x) = -x^3 - 5x^2 - x
Given that f(-x) ≠ -f(x). The function f is not odd.
2. f(x) = sqrt(x)
f(-x) = sqrt(-x) (Imaginary number)
-f(x) = -sqrt(x)
Given that f(-x) ≠ -f(x). The function f is not odd.
3. f(x) = x^2 + x
f(-x) = (-x)^2 -x = x^2 - x
-f(x) = -x^2 - x
Given that f(-x) ≠ -f(x). The function f is not odd.
4. f(x) = -x
f(-x) = - (-x) = x
-f(x) = -(-x) = x
Given that f(-x) = -f(x). The function f is odd.
