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Let $$f : \mathbb{R} \to \mathbb{R}$$ be a function such that
$$f'(x) = (x - 2024)^3 (x - 2025)(x - 2026)^2$$ for all $$x \in \mathbb{R}$$.
Let $$g : \mathbb{R} \to (0, \infty)$$ be a function such that $$g(x) = \sqrt{f(x)}$$ for all $$x \in \mathbb{R}$$.
Then the number of points at which $$g(x)$$ has a local maximum is:
Given :
$$f'(x) = (x - 2024)^3 (x - 2025)(x - 2026)^2$$
$$g(x) = \sqrt{f(x)}$$
Differentiating both sides with respect to $$x$$, we get,
$$g'(x) = \frac{f'(x)}{2\sqrt{f(x)}}$$
$$g'(x) = 0$$ when $$f'(x) = 0$$
$$\Rightarrow$$ Critical points : $$x = 2024, 2025, 2026$$
The factor $$(x - 2026)^2$$ is always positive, so the sign of $$f'(x)$$ depends on $$(x - 2024)^3 (x - 2025)$$.
For $$ x < 2024$$ $$\Rightarrow$$ $$f'(x)$$ is positive $$\Rightarrow$$ $$f(x)$$ is increasing
For $$ 2024 < x < 2025$$ $$\Rightarrow$$ $$f'(x)$$ is negative $$\Rightarrow$$ $$f(x)$$ is decreasing
For $$ x > 2025$$ $$\Rightarrow$$ $$f'(x)$$ is positive $$\Rightarrow$$ $$f(x)$$ is increasing
Hence,
At $$x = 2024$$: $$f$$ changes from increasing to decreasing → local maximum
At $$x = 2025$$: $$f$$ changes from decreasing to increasing → local minimum
At $$x = 2026$$: $$f$$ keeps increasing (no sign change) → no maximum or minimum
Since $$g(x) = \sqrt{f(x)}$$ is a monotonically increasing transformation of $$f(x)$$ (for $$f > 0$$), $$g$$ has the same extremum behavior as $$f$$.
Therefore, $$g(x)$$ has a local maximum only at $$x = 2024$$.
The answer is 1.
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