1. **State the problem:** Find the sum of the first 35 terms of the geometric series: $$8, -12, 18, \ldots$$
2. **Identify the first term and common ratio:** The first term is $$a = 8$$.
The common ratio $$r$$ is found by dividing the second term by the first term:
$$r = \frac{-12}{8} = -\frac{3}{2}$$.
3. **Formula for the sum of the first $$n$$ terms of a geometric series:**
$$S_n = a \frac{1 - r^n}{1 - r}$$
This formula applies when $$r \neq 1$$.
4. **Apply the formula:**
Here, $$n = 35$$, $$a = 8$$, and $$r = -\frac{3}{2}$$.
Calculate $$r^{35}$$:
$$r^{35} = \left(-\frac{3}{2}\right)^{35}$$ (a very large number in magnitude, alternating sign).
5. **Calculate the sum:**
$$S_{35} = 8 \times \frac{1 - \left(-\frac{3}{2}\right)^{35}}{1 - \left(-\frac{3}{2}\right)} = 8 \times \frac{1 - \left(-\frac{3}{2}\right)^{35}}{1 + \frac{3}{2}} = 8 \times \frac{1 - \left(-\frac{3}{2}\right)^{35}}{\frac{5}{2}} = 8 \times \frac{2}{5} \times \left(1 - \left(-\frac{3}{2}\right)^{35}\right) = \frac{16}{5} \left(1 - \left(-\frac{3}{2}\right)^{35}\right)$$
6. **Interpretation:** The sum is $$\frac{16}{5} \left(1 - \left(-\frac{3}{2}\right)^{35}\right)$$.
Since $$\left(-\frac{3}{2}\right)^{35}$$ is a very large number, the sum will be dominated by this term.
**Final answer:**
$$\boxed{S_{35} = \frac{16}{5} \left(1 - \left(-\frac{3}{2}\right)^{35}\right)}$$
Geometric Series Sum Ddacaa
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