Subjects calculus

Integral Rational Root 37440E

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Integral Rational Root 37440E


1. **State the problem:** We want to evaluate the integral $$\int \frac{3x^3 - x^2 + 2x - 4}{\sqrt{x^2 - 3x + 2}} \, dx$$ 2. **Analyze the denominator:** The denominator is $\sqrt{x^2 - 3x + 2}$. Factor the quadratic inside the square root: $$x^2 - 3x + 2 = (x - 1)(x - 2)$$ 3. **Rewrite the integral:** $$\int \frac{3x^3 - x^2 + 2x - 4}{\sqrt{(x - 1)(x - 2)}} \, dx$$ 4. **Consider substitution:** Let’s try to simplify the denominator by substitution. Set $$t = \sqrt{(x - 1)(x - 2)}$$ but this is complicated. Instead, try to express the numerator in terms of the derivative of the denominator’s radicand. 5. **Derivative of the radicand:** $$u = x^2 - 3x + 2$$ $$\frac{du}{dx} = 2x - 3$$ 6. **Try polynomial division:** Divide numerator $3x^3 - x^2 + 2x - 4$ by $\sqrt{x^2 - 3x + 2}$ is complicated, so instead try substitution $u = x^2 - 3x + 2$ and express $x$ in terms of $u$ or rewrite numerator in terms of $u$ and $du$. 7. **Rewrite numerator:** Express numerator as a combination of $u$ and $du$ terms: Note that $u = x^2 - 3x + 2$, so $$x^2 = u + 3x - 2$$ Try to express $3x^3 - x^2 + 2x - 4$ in terms of $x$ and $u$: $$3x^3 - x^2 + 2x - 4 = 3x^3 - (u + 3x - 2) + 2x - 4 = 3x^3 - u - 3x + 2 + 2x - 4 = 3x^3 - u - x - 2$$ 8. **Rewrite $x^3$:** $$x^3 = x \cdot x^2 = x(u + 3x - 2) = x u + 3x^2 - 2x$$ Substitute back: $$3x^3 - u - x - 2 = 3(x u + 3x^2 - 2x) - u - x - 2 = 3x u + 9x^2 - 6x - u - x - 2$$ 9. **Replace $x^2$ again:** $$9x^2 = 9(u + 3x - 2) = 9u + 27x - 18$$ So numerator becomes: $$3x u + 9u + 27x - 18 - 6x - u - x - 2 = 3x u + 9u - u + 27x - 6x - x - 18 - 2 = 3x u + 8u + 20x - 20$$ 10. **Rewrite integral:** $$\int \frac{3x u + 8u + 20x - 20}{\sqrt{u}} \, dx$$ 11. **Express $dx$ in terms of $du$:** Since $u = x^2 - 3x + 2$, $$du = (2x - 3) dx \implies dx = \frac{du}{2x - 3}$$ 12. **Substitute into integral:** $$\int \frac{3x u + 8u + 20x - 20}{\sqrt{u}} \cdot \frac{du}{2x - 3}$$ This is complicated because $x$ and $u$ are mixed. 13. **Alternative approach:** Factor denominator and use substitution $x - 1 = t$ or $x - 2 = t$ to simplify. Try substitution $x - 1 = t$, then $x = t + 1$: Denominator: $$\sqrt{(t)(t - 1)} = \sqrt{t(t - 1)}$$ Numerator: $$3(t + 1)^3 - (t + 1)^2 + 2(t + 1) - 4$$ Calculate numerator: $$(t + 1)^3 = t^3 + 3t^2 + 3t + 1$$ So numerator: $$3(t^3 + 3t^2 + 3t + 1) - (t^2 + 2t + 1) + 2t + 2 - 4 = 3t^3 + 9t^2 + 9t + 3 - t^2 - 2t - 1 + 2t + 2 - 4$$ Simplify: $$3t^3 + 8t^2 + 9t + 0$$ 14. **Integral becomes:** $$\int \frac{3t^3 + 8t^2 + 9t}{\sqrt{t(t - 1)}} \, dt$$ 15. **Rewrite denominator:** $$\sqrt{t(t - 1)} = \sqrt{t} \sqrt{t - 1}$$ 16. **Split integral:** $$\int \frac{3t^3}{\sqrt{t} \sqrt{t - 1}} dt + \int \frac{8t^2}{\sqrt{t} \sqrt{t - 1}} dt + \int \frac{9t}{\sqrt{t} \sqrt{t - 1}} dt$$ Simplify powers: $$3 \int t^{3 - \frac{1}{2}} (t - 1)^{-\frac{1}{2}} dt + 8 \int t^{2 - \frac{1}{2}} (t - 1)^{-\frac{1}{2}} dt + 9 \int t^{1 - \frac{1}{2}} (t - 1)^{-\frac{1}{2}} dt$$ Which is: $$3 \int t^{\frac{5}{2}} (t - 1)^{-\frac{1}{2}} dt + 8 \int t^{\frac{3}{2}} (t - 1)^{-\frac{1}{2}} dt + 9 \int t^{\frac{1}{2}} (t - 1)^{-\frac{1}{2}} dt$$ 17. **Use substitution:** Let $$w = \sqrt{\frac{t}{t - 1}}$$ or use trigonometric substitution for $\sqrt{t(t-1)}$ but this is complex. 18. **Summary:** The integral is complicated and requires advanced substitution or special functions. **Final answer:** The integral does not simplify easily with elementary functions and likely requires advanced techniques or numerical methods. **Slug:** integral rational root **Subject:** calculus