The given series is
\[ \sum_{k=1}^{\infty} 6\left(-\frac{2}{3}\right)^{k-1}. \]
The first term \( a \) is the term when \( k = 1 \), which is
\[ a = 6\left(-\frac{2}{3}\right)^{1-1} = 6 \times 1 = 6. \]
The common ratio \( r \) is the factor by which each
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