3arisan $$ 18, x, 2, y, \ldots $$. adalah barisan geometri dengan perbandingan positif. Nilai $$ x+6 y $$ a. -26 b. -10 c. 26 d. 0 e. 10

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1. Since the sequence $$ 18,\, x,\, 2,\, y,\, \ldots $$ is geometric with a positive ratio, let the common ratio be $$ r $$.
2. The terms can be written as:
   - First term: $$ a_1 = 18 $$
   - Second term: $$ a_2 = 18r = x $$
   - Third term: $$ a_3 = 18r^2 = 2 $$
   - Fourth term: $$ a_4 = 18r^3 = y $$
3. Using the third term:
   $$
   18r^2 = 2 \quad \Longrightarrow \quad r^2 = \frac{2}{18} = \frac{1}{9}
   $$
4. Since the common ratio is positive:
   $$
   r = \frac{1}{3}
   $$
5. Find $$ x $$ using the second term:
   $$
   x = 18r = 18 \times \frac{1}{3} = 6
   $$
6. Find $$ y $$ using the fourth term:
   $$
   y = 18r^3 = 18 \times \left(\frac{1}{3}\right)^3 = 18 \times \frac{1}{27} = \frac{18}{27} = \frac{2}{3}
   $$
7. Calculate $$ x + 6y $$:
   $$
   x + 6y = 6 + 6 \times \frac{2}{3} = 6 + 4 = 10
   $$

Thus, the value of $$ x + 6y $$ is $$ 10 $$.
$$ x + 6y = 10 $$, so the answer is 10.

3arisan \( 18, x, 2, y, \ldots \). adalah barisan geometri dengan perbandingan positif. Nilai \( x+6 y \) a. -26 b. -10 c. 26 d. 0 e. 10

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