1. **State the problem:** Find the values of $x$, $y$, and $z$ such that the vector $(x y, x + y, z - 1)$ equals $(4, 2, 3)$.
2. **Set up equations:** Since the vectors are equal, their corresponding components must be equal:
$$x y = 4$$
$$x + y = 2$$
$$z - 1 = 3$$
3. **Solve for $z$:** From the third equation,
$$z - 1 = 3 \implies z = 4$$
4. **Solve for $x$ and $y$:** From the second equation,
$$x + y = 2$$
From the first equation,
$$x y = 4$$
5. **Use substitution or quadratic approach:** Let $y = 2 - x$ from the second equation. Substitute into the first:
$$x(2 - x) = 4$$
$$2x - x^2 = 4$$
$$-x^2 + 2x - 4 = 0$$
Multiply both sides by $-1$:
$$x^2 - 2x + 4 = 0$$
6. **Solve quadratic equation:** The quadratic is
$$x^2 - 2x + 4 = 0$$
Calculate the discriminant:
$$\Delta = (-2)^2 - 4 \times 1 \times 4 = 4 - 16 = -12$$
Since $\Delta < 0$, there are no real solutions for $x$ and $y$.
7. **Interpretation:** The system has no real solutions for $x$ and $y$, but complex solutions exist.
8. **Find complex solutions:** Using quadratic formula,
$$x = \frac{2 \pm \sqrt{-12}}{2} = 1 \pm i\sqrt{3}$$
Then,
$$y = 2 - x = 1 \mp i\sqrt{3}$$
**Final answer:**
$$x = 1 \pm i\sqrt{3}, \quad y = 1 \mp i\sqrt{3}, \quad z = 4$$
Vector Equation 9F1237
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