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The problem provided is about an arithmetic sequence, where two terms are given:

- \( U_8 = 18 \) (the 8th term is 18)
- \( U_{15} = 46 \) (the 15th term is 46)

The questions ask to determine:
1. **The common difference (\(d\))** and the **first term (\(U_1\))** of the sequence.
2. **The 12th term** of the sequence (\(U_{12}\)).
3. **The sum of the first 10 terms** of the sequence.

### Solution:

For an arithmetic sequence, the general formula for the \(n\)-th term is:
\[
U_n = U_1 + (n - 1) \cdot d
\]
Where:
- \(U_n\) is the \(n\)-th term,
- \(U_1\) is the first term,
- \(d\) is the common difference,
- \(n\) is the term's position.

### Step 1: Finding the Common Difference (\(d\)) and the First Term (\(U_1\))

We know the values of \(U_8\) and \(U_{15}\), so let's write two equations:

\[
U_8 = U_1 + 7d = 18 \tag{1}
\]
\[
U_{15} = U_1 + 14d = 46 \tag{2}
\]

By subtracting equation (1) from equation (2):
\[
(U_1 + 14d) - (U_1 + 7d) = 46 - 18
\]
\[
7d = 28
\]
\[
d = 4
\]

Now substitute \(d = 4\) back into equation (1):
\[
U_1 + 7 \cdot 4 = 18
\]
\[
U

Pada suatu barisan aritmatika diketahui U8 = 18 dan U15 = 46. Tentukan a) beda dan suku pertama barisan tersebut b) besar suku ke-12 c) 10 suku pertama barisan tersebut.

Solve an arithmetic sequence problem where U8 = 18 and U15 = 46. Learn how to find the common difference, the first term, the 12th term, and the sum of the first 10 terms using arithmetic formulas.

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