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