1. **Problem:** Given one complex solution to the quadratic equation $f(x) = x^2 + 2x + 5$ is $w_1 = -1 + 2i$, find the other solution $w_2$ and state the relationship between $w_1$ and $w_2$.
2. **Formula and rules:** For a quadratic equation $ax^2 + bx + c = 0$, the sum and product of roots $w_1$ and $w_2$ satisfy:
$$w_1 + w_2 = -\frac{b}{a}$$
$$w_1 w_2 = \frac{c}{a}$$
Since coefficients are real, complex roots occur in conjugate pairs.
3. **Find $w_2$:** Given $w_1 = -1 + 2i$, the other root is its complex conjugate:
$$w_2 = -1 - 2i$$
4. **Relationship:** $w_1$ and $w_2$ are complex conjugates.
---
5. **Problem:** Determine the modulus of $w_1 = -1 + 2i$.
6. **Formula:** The modulus of a complex number $a + bi$ is:
$$|w| = \sqrt{a^2 + b^2}$$
7. **Calculate modulus:**
$$|w_1| = \sqrt{(-1)^2 + (2)^2} = \sqrt{1 + 4} = \sqrt{5}$$
**Final answers:**
- The other solution is $w_2 = -1 - 2i$.
- $w_1$ and $w_2$ are complex conjugates.
- The modulus of $w_1$ is $\sqrt{5}$.
Complex Roots Ea454A
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.