Concept:The derivative of an even function is always an odd function.
Explanation:For an even function, we have
f(−x)=f(x) for all
x∈R.
Differentiate both sides with respect to
x.
Using the chain rule on the left side:
dxd​f(−x)=f′(−x)⋅(−1)=−f′(−x)And the derivative of the right side is:
dxd​f(x)=f′(x)Equating both derivatives gives:
−f′(−x)=f′(x)Rearranging, we get:
f′(−x)=−f′(x)This is exactly the defining condition of an odd function.
Therefore, wherever
f′(x) exists, it must be an odd function.
Options A, B, and C are not necessarily true for every even function.
Answer:Option D:
f′(x) is an odd function.