1. **State the problem:** Solve the polynomial equation $$x^5 - 4x^4 + 5x^3 - 4x^2 + 4x = 0$$ for $x$.
2. **Factor out the common factor:** Notice every term contains $x$, so factor it out:
$$x(x^4 - 4x^3 + 5x^2 - 4x + 4) = 0$$
3. **Set each factor equal to zero:**
- From $x = 0$, we get one root: $$x = 0$$
- Now solve the quartic: $$x^4 - 4x^3 + 5x^2 - 4x + 4 = 0$$
4. **Try to factor the quartic:** Look for quadratic factors:
Assume $$ (x^2 + ax + b)(x^2 + cx + d) = x^4 - 4x^3 + 5x^2 - 4x + 4 $$
Expanding:
$$x^4 + (a + c)x^3 + (ac + b + d)x^2 + (ad + bc)x + bd = x^4 - 4x^3 + 5x^2 - 4x + 4$$
Match coefficients:
- $a + c = -4$
- $ac + b + d = 5$
- $ad + bc = -4$
- $bd = 4$
5. **Find integer factors of 4 for $b$ and $d$:** Possible pairs: (1,4), (2,2), (4,1), (-1,-4), (-2,-2), (-4,-1)
Try $b=2$, $d=2$:
- $bd=4$ correct
- $ac + 2 + 2 = 5
ightarrow ac + 4 = 5
ightarrow ac = 1$
- $a + c = -4$
- $ad + bc = a*2 + b*c = 2a + 2c = -4$
From $a + c = -4$, multiply both sides by 2:
$$2a + 2c = -8$$
But from above $2a + 2c = -4$, contradiction.
Try $b=1$, $d=4$:
- $bd=4$ correct
- $ac + 1 + 4 = 5
ightarrow ac = 0$
- $a + c = -4$
- $ad + bc = 4a + c = -4$
From $a + c = -4$, $c = -4 - a$
Substitute into $4a + c = -4$:
$$4a + (-4 - a) = -4
ightarrow 3a - 4 = -4
ightarrow 3a = 0
ightarrow a = 0$$
Then $c = -4 - 0 = -4$
Check $ac = 0 * (-4) = 0$ correct.
6. **So factors are:**
$$(x^2 + 0x + 1)(x^2 - 4x + 4) = (x^2 + 1)(x^2 - 4x + 4)$$
7. **Solve each quadratic:**
- $x^2 + 1 = 0
ightarrow x^2 = -1
ightarrow x = \pm i$
- $x^2 - 4x + 4 = 0$ is a perfect square:
$$ (x - 2)^2 = 0
ightarrow x = 2$$
8. **Summary of roots:**
$$x = 0, 2, 2, i, -i$$
**Final answer:** The solutions to the equation are $$x = 0, x = 2 \text{ (double root)}, x = i, x = -i$$.
Polynomial Roots 6B70E5
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