1. **State the problem:** Express the rational function $$\frac{x^2 + 2x - 8}{x^3 (x^4 - 2)}$$ in partial fractions.
2. **Identify the denominator factors:** The denominator is $$x^3 (x^4 - 2)$$. Here, $$x^3$$ is a repeated linear factor and $$x^4 - 2$$ is an irreducible quartic polynomial.
3. **Set up the partial fraction decomposition:** For the repeated linear factor $$x^3$$, we write terms with powers 1 to 3:
$$\frac{A}{x} + \frac{B}{x^2} + \frac{C}{x^3}$$
For the quartic polynomial $$x^4 - 2$$, since it is irreducible, we use a general linear numerator:
$$\frac{Dx^3 + Ex^2 + Fx + G}{x^4 - 2}$$
4. **Write the full decomposition:**
$$\frac{x^2 + 2x - 8}{x^3 (x^4 - 2)} = \frac{A}{x} + \frac{B}{x^2} + \frac{C}{x^3} + \frac{Dx^3 + Ex^2 + Fx + G}{x^4 - 2}$$
5. **Multiply both sides by the denominator to clear fractions:**
$$x^2 + 2x - 8 = A x^2 (x^4 - 2) + B x (x^4 - 2) + C (x^4 - 2) + (Dx^3 + Ex^2 + Fx + G) x^3$$
6. **Expand and collect like terms:**
Expand each term and group powers of $$x$$ to form a polynomial identity.
7. **Equate coefficients of corresponding powers of $$x$$:**
This will give a system of equations to solve for $$A, B, C, D, E, F, G$$.
8. **Solve the system:**
Use substitution or matrix methods to find the values of the constants.
9. **Write the final partial fraction decomposition:**
Substitute the constants back into the decomposition formula.
This process expresses the given rational function as a sum of simpler fractions, which is useful for integration or further algebraic manipulation.
Partial Fractions 137C4F
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