\( 110 = \frac{n}{2}(10 + 3n - 3) \)
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- #### 62.832 cm² (using π ≈ 3.14159)
- The sum of the first n terms of an arithmetic sequence is given by \( S_n = \frac{n}{2}(2a + (n-1)d) \). If \( a = 5 \), \( d = 3 \), and \( S_n = 110 \), find n.
- \( 110 = \frac{n}{2}(2 \times 5 + (n-1) \times 3) \)
- \( 110 = \frac{n}{2}(3n + 7) \)
- \( 220 = n(3n + 7) \)
- \( 3n^2 + 7n - 220 = 0 \)
