1. **State the problem:** We need to evaluate the definite integral $$\int_1^{10} \frac{2624}{x^2 + x + 1} \, dx$$.
2. **Recall the formula and approach:** The integral of the form $$\int \frac{1}{x^2 + bx + c} \, dx$$ can be solved by completing the square in the denominator and using the arctangent formula:
$$\int \frac{dx}{(x + \frac{b}{2})^2 + (c - \frac{b^2}{4})} = \frac{1}{\sqrt{c - \frac{b^2}{4}}} \arctan \left( \frac{x + \frac{b}{2}}{\sqrt{c - \frac{b^2}{4}}} \right) + C$$
3. **Complete the square for the denominator:**
$$x^2 + x + 1 = \left(x + \frac{1}{2}\right)^2 + 1 - \frac{1}{4} = \left(x + \frac{1}{2}\right)^2 + \frac{3}{4}$$
4. **Rewrite the integral:**
$$\int_1^{10} \frac{2624}{\left(x + \frac{1}{2}\right)^2 + \frac{3}{4}} \, dx = 2624 \int_1^{10} \frac{dx}{\left(x + \frac{1}{2}\right)^2 + \left(\frac{\sqrt{3}}{2}\right)^2}$$
5. **Use substitution:** Let $$u = x + \frac{1}{2}$$, so when $$x=1$$, $$u=1.5$$, and when $$x=10$$, $$u=10.5$$.
6. **Apply the arctangent integral formula:**
$$\int \frac{du}{u^2 + a^2} = \frac{1}{a} \arctan \left( \frac{u}{a} \right) + C$$ where $$a = \frac{\sqrt{3}}{2}$$.
7. **Evaluate the definite integral:**
$$2624 \times \frac{1}{\frac{\sqrt{3}}{2}} \left[ \arctan \left( \frac{u}{\frac{\sqrt{3}}{2}} \right) \right]_{1.5}^{10.5} = 2624 \times \frac{2}{\sqrt{3}} \left[ \arctan \left( \frac{10.5}{\frac{\sqrt{3}}{2}} \right) - \arctan \left( \frac{1.5}{\frac{\sqrt{3}}{2}} \right) \right]$$
8. **Simplify the arguments:**
$$\frac{10.5}{\frac{\sqrt{3}}{2}} = \frac{10.5 \times 2}{\sqrt{3}} = \frac{21}{\sqrt{3}}$$
$$\frac{1.5}{\frac{\sqrt{3}}{2}} = \frac{1.5 \times 2}{\sqrt{3}} = \frac{3}{\sqrt{3}} = \sqrt{3}$$
9. **Final expression:**
$$\int_1^{10} \frac{2624}{x^2 + x + 1} \, dx = \frac{5248}{\sqrt{3}} \left( \arctan \left( \frac{21}{\sqrt{3}} \right) - \arctan (\sqrt{3}) \right)$$
10. **Numerical approximation:**
$$\arctan(\sqrt{3}) = \frac{\pi}{3} \approx 1.0472$$
$$\arctan \left( \frac{21}{\sqrt{3}} \right) \approx 1.523$$
So,
$$\int_1^{10} \frac{2624}{x^2 + x + 1} \, dx \approx \frac{5248}{1.732} (1.523 - 1.0472) = 3028.6 \times 0.4758 \approx 1440.5$$
**Answer:** $$\boxed{1440.5}$$
Integral Evaluation C36A78
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