1. **State the problem:**
Given two complex numbers $z_1 = 5 + 3i$ and $z_2 = 2 - i$,
(a) find their conjugates $\overline{z_1}$ and $\overline{z_2}$.
(b) Determine the value of $k$ if $\frac{1}{z_2} = k \overline{z_1}$.
2. **Recall the formula for conjugate:**
The conjugate of a complex number $a + bi$ is $a - bi$.
3. **Find the conjugates:**
$$\overline{z_1} = 5 - 3i$$
$$\overline{z_2} = 2 + i$$
4. **Express $\frac{1}{z_2}$:**
To find $\frac{1}{z_2}$, multiply numerator and denominator by the conjugate of $z_2$:
$$\frac{1}{2 - i} \times \frac{2 + i}{2 + i} = \frac{2 + i}{(2)^2 - (-1)^2} = \frac{2 + i}{4 + 1} = \frac{2 + i}{5}$$
5. **Set up the equation:**
$$\frac{1}{z_2} = k \overline{z_1} \implies \frac{2 + i}{5} = k (5 - 3i)$$
6. **Solve for $k$:**
Divide both sides by $5 - 3i$:
$$k = \frac{\frac{2 + i}{5}}{5 - 3i} = \frac{2 + i}{5} \times \frac{1}{5 - 3i}$$
Multiply numerator and denominator by the conjugate of the denominator:
$$k = \frac{2 + i}{5} \times \frac{5 + 3i}{(5)^2 - (-3)^2} = \frac{2 + i}{5} \times \frac{5 + 3i}{25 + 9} = \frac{2 + i}{5} \times \frac{5 + 3i}{34}$$
7. **Multiply the numerators:**
$$(2 + i)(5 + 3i) = 2 \times 5 + 2 \times 3i + i \times 5 + i \times 3i = 10 + 6i + 5i + 3i^2 = 10 + 11i + 3(-1) = 10 + 11i - 3 = 7 + 11i$$
8. **Combine all:**
$$k = \frac{7 + 11i}{5 \times 34} = \frac{7 + 11i}{170}$$
**Final answer:**
$$\overline{z_1} = 5 - 3i$$
$$\overline{z_2} = 2 + i$$
$$k = \frac{7 + 11i}{170}$$
Complex Conjugates 5D7Cb7
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