Int(3x^3-x^2+2x-4)/√(x^2-3x+2)dx
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Int(3x^3-x^2+2x-4)/√(x^2-3x+2)dx
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Asked by: Test User 100000
Created at: 2025-09-17 22:37:22
Asked by: Test User 100000
Created at: 2025-09-17 22:37:22
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To evaluate \(\int \frac{3x^3 - x^2 + 2x - 4}{\sqrt{x^2 - 3x + 2}} \, dx\):
1. **Factor the denominator**:
\[
x^2 - 3x + 2 = (x - 1)(x - 2)
\]
2. **Use substitution for the square root**:
Let \(t = \sqrt{x^2 - 3x + 2}\).
Alternatively, since the denominator involves a quadratic, consider substitution to simplify the expression.
3. **Complete the square inside the square root**:
\[
x^2 - 3x + 2 = (x - \frac{3}{2})^2 - \frac{9}{4} + 2 = (x - \frac{3}{2})^2 - \frac{1}{4}
\]
4. **Substitute \(u = x - \frac{3}{2}\)**:
\[
du = dx
\]
The integral becomes:
\[
\int \frac{3x^3 - x^2 + 2x - 4}{\sqrt{u^2 - \frac{1}{4}}} \, dx
\]
But since \(x = u + \frac{3}{2}\), rewrite numerator in terms of \(u\).
5. **Rewrite numerator in terms of \(u\)**:
- \(x = u + \frac{3}{2}\)
- \(x^2 = u^2 + 3u + \frac{9}{4}\)
- \(x^3 = u^3 + \frac{9}{2} u^2 + \frac{27}{4} u + \frac{27}{8}\)
Plug into numerator:
\[
3x^3 - x^2 + 2x - 4
\]
becomes a polynomial in \(u\).
6. **Perform polynomial expansion**:
- \(3x^3 = 3u^3 + \frac{27}{2} u^2 + \frac{81}{4} u + \frac{81}{8}\)
- \(-x^2 = -u^2 - 3u - \frac{9}{4}\)
- \(2x = 2u + 3\)
- \(-4\) stays the same
Sum:
\[
(3u^3) + \left(\frac{27}{2} u^2 - u^2\right) + \left(\frac{81}{4} u - 3u + 2u\right) + \left(\frac{81}{8} - \frac{9}{4} + 3 - 4\right)
\]
Simplify each group:
- \(3u^3\)
- \(\frac{27}{2} u^2 - u^2 = \frac{27}{2} u^2 - \frac{2}{2} u^2 = \frac{25}{2} u^2\)
- \(\frac{81}{4} u - 3u + 2u = \frac{81}{4} u - \frac{12}{4} u + \frac{8}{4} u = \frac{77}{4} u\)
- Constants: \(\frac{81}{8} - \frac{18}{8} + \frac{24}{8} - \frac{32}{8} = \frac{81 - 18 + 24 - 32}{8} = \frac{55}{8}\)
So numerator:
\[
3u^3 + \frac{25}{2} u^2 + \frac{77}{4} u + \frac{55}{8}
\]
7. **Rewrite the integral**:
\[
\int \frac{3u^3 + \frac{25}{2} u^2 + \frac{77}{4} u + \frac{55}{8}}{\sqrt{u^2 - \frac{1}{4}}} du
\]
8. **Express as sum of integrals**:
\[
\int \frac{3u^3}{\sqrt{u^2 - \frac{1}{4}}} du + \frac{25}{2} \int \frac{u^2}{\sqrt{u^2 - \frac{1}{4}}} du + \frac
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