Concept:
We are given nested derivative relations:
\[
f'(x)=g(x+1), \quad g'(x)=h(x-1)
\]
To find \(f''(x)\), we differentiate \(f'(x)\), then substitute carefully using the given relations.
Step 1: Differentiate \(f'(x)\)
\[
f''(x) = \frac{d}{dx}[g(x+1)]
\]
Using chain rule:
\[
f''(x) = g'(x+1)
\]
Step 2: Use given relation for \(g'(x)\)
We know:
\[
g'(x) = h(x-1)
\]
Replace \(x\) with \(x+1\):
\[
g'(x+1) = h((x+1)-1)
\]
Step 3: Simplify
\[
g'(x+1) = h(x)
\]
Thus:
\[
f''(x) = h(x)
\]
Step 4: Evaluate at \(2x\)
\[
f''(2x) = h(2x)
\]
Step 5: Final Answer
\[
\boxed{h(2x)}
\]