Question: Ex1 If $\frac{2x - yi}{1 + 2i}$, $\frac{3 - i}{1 - i}$ are conjugated find the real value of $x,y$
1. **State the problem:**
Find the real values of $x$ and $y$ such that the complex fractions $\frac{2x - yi}{1 + 2i}$ and $\frac{3 - i}{1 - i}$ are conjugates.
2. **Recall the conjugate property:**
If two complex numbers $z$ and $w$ are conjugates, then $z = \overline{w}$.
3. **Express the conjugate:**
The conjugate of $\frac{3 - i}{1 - i}$ is $\overline{\frac{3 - i}{1 - i}} = \frac{3 + i}{1 + i}$.
4. **Set the equality:**
$$\frac{2x - yi}{1 + 2i} = \frac{3 + i}{1 + i}$$
5. **Cross multiply:**
$$(2x - yi)(1 + i) = (3 + i)(1 + 2i)$$
6. **Expand both sides:**
Left side:
$$ (2x)(1) + (2x)(i) - y i (1) - y i (i) = 2x + 2x i - y i - y i^2 $$
Since $i^2 = -1$, this becomes:
$$ 2x + 2x i - y i + y = (2x + y) + i(2x - y) $$
Right side:
$$ 3(1) + 3(2i) + i(1) + i(2i) = 3 + 6i + i + 2 i^2 = 3 + 7i + 2(-1) = 3 + 7i - 2 = 1 + 7i $$
7. **Equate real and imaginary parts:**
Real parts:
$$ 2x + y = 1 $$
Imaginary parts:
$$ 2x - y = 7 $$
8. **Solve the system:**
Add the two equations:
$$ (2x + y) + (2x - y) = 1 + 7 \Rightarrow 4x = 8 \Rightarrow x = 2 $$
Substitute $x=2$ into $2x + y = 1$:
$$ 2(2) + y = 1 \Rightarrow 4 + y = 1 \Rightarrow y = 1 - 4 = -3 $$
**Final answer:**
$$ x = 2, \quad y = -3 $$