1. **State the problem:**
We have three sets:
- $\xi = \{x: x \text{ is an integer and } -4 \leq x \leq 2\}$
- $P = \{x: 3x - 1 < 2\}$
- $Q = \{x: 2x^2 + 7x + 3 = 0\}$
We need to find:
(a) $P'$ (the complement of $P$ relative to $\xi$),
(b) $P \cap Q$ (the intersection of $P$ and $Q$),
(c) $P \cup Q$ (the union of $P$ and $Q$).
2. **Find the elements of $\xi$:**
$$\xi = \{-4, -3, -2, -1, 0, 1, 2\}$$
3. **Find the elements of $P$:**
Solve the inequality:
$$3x - 1 < 2$$
Add 1 to both sides:
$$3x - 1 + 1 < 2 + 1$$
$$3x < 3$$
Divide both sides by 3:
$$\cancel{3}x < \cancel{3}$$
$$x < 1$$
Since $x$ must be an integer in $\xi$, elements of $P$ are all integers less than 1 in $\xi$:
$$P = \{-4, -3, -2, -1, 0\}$$
4. **Find the elements of $Q$:**
Solve the quadratic equation:
$$2x^2 + 7x + 3 = 0$$
Use the quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=2$, $b=7$, $c=3$.
Calculate the discriminant:
$$\Delta = 7^2 - 4 \times 2 \times 3 = 49 - 24 = 25$$
Calculate roots:
$$x = \frac{-7 \pm \sqrt{25}}{2 \times 2} = \frac{-7 \pm 5}{4}$$
Two roots:
$$x_1 = \frac{-7 + 5}{4} = \frac{-2}{4} = -\frac{1}{2}$$
$$x_2 = \frac{-7 - 5}{4} = \frac{-12}{4} = -3$$
Since $Q$ contains integers in $\xi$ satisfying the equation, only $x = -3$ is in $Q$ (because $-\frac{1}{2}$ is not an integer).
So:
$$Q = \{-3\}$$
5. **Find (a) $P'$:**
$P'$ is the complement of $P$ in $\xi$, i.e., elements in $\xi$ not in $P$:
$$P' = \xi \setminus P = \{-4, -3, -2, -1, 0, 1, 2\} \setminus \{-4, -3, -2, -1, 0\} = \{1, 2\}$$
6. **Find (b) $P \cap Q$:**
Intersection of $P$ and $Q$:
$$P \cap Q = \{-4, -3, -2, -1, 0\} \cap \{-3\} = \{-3\}$$
7. **Find (c) $P \cup Q$:**
Union of $P$ and $Q$:
$$P \cup Q = \{-4, -3, -2, -1, 0\} \cup \{-3\} = \{-4, -3, -2, -1, 0\}$$
**Final answers:**
- (a) $P' = \{1, 2\}$
- (b) $P \cap Q = \{-3\}$
- (c) $P \cup Q = \{-4, -3, -2, -1, 0\}$
Set Operations De2C3A
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