1. **State the problem:**
We want to find constants $a$ and $b$ such that
$$\frac{1 - x + 6x^2}{x - x^3} = \frac{a}{x - 2} - \frac{b}{x - 1}.$$
2. **Rewrite the denominator:**
Note that
$$x - x^3 = x(1 - x^2) = x(1 - x)(1 + x),$$
but since the right side has denominators $x-2$ and $x-1$, we will clear denominators by multiplying both sides by $(x-2)(x-1)(x - x^3)$ to find $a$ and $b$.
3. **Multiply both sides by the common denominator:**
Multiply both sides by $(x - 2)(x - 1)(x - x^3)$:
$$ (1 - x + 6x^2)(x - 2)(x - 1) = a(x - x^3)(x - 1) - b(x - x^3)(x - 2).$$
4. **Simplify the right side:**
Recall $x - x^3 = x(1 - x^2) = x(1 - x)(1 + x)$.
5. **Evaluate at convenient values to solve for $a$ and $b$: **
- Let $x=2$ (to eliminate $b$ term):
$$\frac{1 - 2 + 6(2)^2}{2 - 2^3} = \frac{a}{2 - 2} - \frac{b}{2 - 1}$$
The left side denominator is $2 - 8 = -6$, numerator is $1 - 2 + 24 = 23$, so left side is $\frac{23}{-6} = -\frac{23}{6}$.
Right side at $x=2$ is $\frac{a}{0} - \frac{b}{1}$, undefined for $a$ term, so better to use the equation after clearing denominators.
Using the cleared equation:
At $x=2$:
$$(1 - 2 + 6(2)^2)(2 - 2)(2 - 1) = a(2 - 2^3)(2 - 1) - b(2 - 2^3)(2 - 2)$$
Left side: $(1 - 2 + 24)(0)(1) = 0$
Right side: $a(2 - 8)(1) - b(2 - 8)(0) = a(-6)(1) - 0 = -6a$
So,
$$0 = -6a \implies a = 0.$$
- Let $x=1$ (to eliminate $a$ term):
At $x=1$:
$$(1 - 1 + 6(1)^2)(1 - 2)(1 - 1) = a(1 - 1^3)(1 - 1) - b(1 - 1^3)(1 - 2)$$
Left side: $(1 - 1 + 6)(-1)(0) = 0$
Right side: $a(0)(0) - b(0)(-1) = 0$
This gives no information.
6. **Use another value, say $x=0$:**
At $x=0$:
$$(1 - 0 + 0)(0 - 2)(0 - 1) = a(0 - 0)(0 - 1) - b(0 - 0)(0 - 2)$$
Left side: $1 \times (-2) \times (-1) = 2$
Right side: $a(0)(-1) - b(0)(-2) = 0$
No information again.
7. **Rewrite the original equation with $a=0$ and solve for $b$: **
$$\frac{1 - x + 6x^2}{x - x^3} = - \frac{b}{x - 1}.$$
Multiply both sides by $(x - x^3)(x - 1)$:
$$(1 - x + 6x^2)(x - 1) = -b(x - x^3).$$
Expand left side:
$$(1 - x + 6x^2)(x - 1) = (1)(x - 1) - x(x - 1) + 6x^2(x - 1) = (x - 1) - (x^2 - x) + 6x^3 - 6x^2$$
Simplify:
$$x - 1 - x^2 + x + 6x^3 - 6x^2 = 6x^3 - 7x^2 + 2x - 1.$$
Right side:
$$-b(x - x^3) = -b x + b x^3 = b x^3 - b x.$$
8. **Equate coefficients:**
$$6x^3 - 7x^2 + 2x - 1 = b x^3 - b x.$$
Match powers of $x$:
- For $x^3$: $6 = b$
- For $x^2$: $-7 = 0$ (contradiction)
- For $x$: $2 = -b$
- For constant: $-1 = 0$ (contradiction)
Contradiction means the original assumption $a=0$ is wrong or the form is not correct.
9. **Try partial fraction decomposition directly:**
Rewrite denominator:
$$x - x^3 = x(1 - x^2) = x(1 - x)(1 + x).$$
The right side has denominators $x-2$ and $x-1$, but the left denominator factors differently.
10. **Conclusion:**
The given equation cannot hold for constants $a,b$ with denominators $x-2$ and $x-1$ because the denominators do not match the factorization of the left side.
**Final answer:**
$$a = 0, \quad b = 0$$
No such constants $a,b$ satisfy the equation as given.
Partial Fractions 949B57
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