Solve System 7E27D2
1. **Stating the problem:** Solve the system of equations for $x$ and $y$:
$$\begin{cases} xy = 3 \\ x^2 + y^2 = 10 \end{cases}$$
2. **Use the identity:**
$$ (x + y)^2 = x^2 + 2xy + y^2 $$
This helps relate $x + y$ to $xy$ and $x^2 + y^2$.
3. **Calculate $(x + y)^2$:**
Multiply the first equation by 2 and add to the second:
$$ 2xy + (x^2 + y^2) = 2 \times 3 + 10 = 6 + 10 = 16 $$
So,
$$ (x + y)^2 = 16 $$
4. **Find $x + y$:**
$$ x + y = \pm 4 $$
5. **Form quadratic equations:**
Since $x$ and $y$ are roots of the quadratic equation
$$ t^2 - (x + y)t + xy = 0 $$
we have two cases:
- For $x + y = 4$:
$$ t^2 - 4t + 3 = 0 $$
- For $x + y = -4$:
$$ t^2 + 4t + 3 = 0 $$
6. **Solve the quadratics:**
- For $t^2 - 4t + 3 = 0$:
$$ (t - 1)(t - 3) = 0 \implies t = 1, 3 $$
- For $t^2 + 4t + 3 = 0$:
$$ (t + 1)(t + 3) = 0 \implies t = -1, -3 $$
7. **Write solution pairs:**
From the roots, the four solution pairs $(x,y)$ are:
$$ (1, 3), (3, 1), (-1, -3), (-3, -1) $$
**Final answer:**
$$ \boxed{\{(1,3), (3,1), (-1,-3), (-3,-1)\}} $$