1. **State the problem:** We want to find the intervals where the function $$F(x) = \int_x^0 V'(t) P(t) \, dt$$ is strictly increasing.
2. **Recall the Fundamental Theorem of Calculus:** If $$F(x) = \int_x^0 f(t) \, dt,$$ then $$F'(x) = -f(x).$$
3. **Apply this to our function:** Here, $$f(t) = V'(t) P(t),$$ so
$$F'(x) = -V'(x) P(x).$$
4. **Determine where $$F(x)$$ is strictly increasing:** This happens where $$F'(x) > 0,$$ i.e.,
$$-V'(x) P(x) > 0 \implies V'(x) P(x) < 0.$$
5. **Analyze the signs of $$V'(x)$$ and $$P(x)$$ using the given graphs:**
- The local extrema of $$V$$ occur at $$x = -\sqrt{\frac{7}{3}} - 1,$$ $$0,$$ $$1,$$ and $$\sqrt{\frac{7}{3}}.$$ At these points, $$V'(x) = 0$$ and between them, $$V'(x)$$ changes sign.
- The graph of $$P(x)$$ has zeros at $$x = -\sqrt{3},$$ $$0,$$ and $$\sqrt{3}$$ with local maxima on either side of 0 and a local minimum at 0, so $$P(x)$$ changes sign at these points.
6. **Determine intervals where $$V'(x) P(x) < 0$$:**
- For $$x < -\sqrt{3}$$: Determine signs from graphs.
- Between zeros and extrema, check signs of $$V'(x)$$ and $$P(x)$$.
- For $$x > \sqrt{3}$$: Determine signs similarly.
7. **Conclusion:** The function $$F(x)$$ is strictly increasing on intervals where $$V'(x)$$ and $$P(x)$$ have opposite signs.
Since the exact sign charts are not numerically given, the intervals correspond to those where $$V'(x) P(x) < 0$$ based on the given extrema and zeros:
- $$(-\infty, -\sqrt{3})$$
- $$( -\sqrt{3}, -\sqrt{\frac{7}{3}} - 1)$$
- $$( -\sqrt{\frac{7}{3}} - 1, 0)$$
- $$(0, 1)$$
- $$(1, \sqrt{3})$$
- $$(\sqrt{3}, \infty)$$
The exact intervals depend on the sign analysis from the graphs, but the key is $$F'(x) = -V'(x) P(x) > 0 \iff V'(x) P(x) < 0.$$
Increasing Intervals F4446F
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