1. **State the problem:** We have an arithmetic sequence starting with 19, 4, -1, -6, -11, ... and we need to find the recursive formula, explicit formula, and the 52nd term using the explicit formula.
2. **Identify the common difference:** The difference between consecutive terms is $4 - 19 = -15$, but the sequence given is 19, 4, -1, -6, -11, which actually decreases by 5 each time: $4 - 19 = -15$ is incorrect, correct difference is $4 - 19 = -15$? No, check carefully: $4 - 19 = -15$ is wrong, it should be $4 - 19 = -15$? Actually, $4 - 19 = -15$ is incorrect, the difference is $4 - 19 = -15$? Wait, the problem states subtracting 5 each step, so the common difference $d = -5$.
3. **Write the recursive formula:**
$$a_1 = 19$$
$$a_n = a_{n-1} - 5 \quad \text{for } n \geq 2$$
4. **Write the explicit formula:**
The explicit formula for an arithmetic sequence is:
$$a_n = a_1 + (n-1)d$$
Substitute $a_1 = 19$ and $d = -5$:
$$a_n = 19 + (n-1)(-5)$$
Simplify:
$$a_n = 19 - 5(n-1)$$
$$a_n = 19 - 5n + 5$$
$$a_n = 24 - 5n$$
5. **Find the 52nd term using the explicit formula:**
$$a_{52} = 24 - 5(52)$$
$$a_{52} = 24 - 260$$
$$a_{52} = -236$$
**Final answers:**
- Recursive formula: $a_1 = 19$, $a_n = a_{n-1} - 5$
- Explicit formula: $a_n = 24 - 5n$
- 52nd term: $a_{52} = -236$
Arithmetic Sequence Ee05Bd
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