Respuesta :
We are given the Geometric Series:
[tex]2 + \frac{2}{3} + \frac{2}{9} + \frac{2}{27} + \frac{2}{81} + \frac{2}{243} + \frac{2}{729}[/tex]
which can be rewritten as:
[tex]2 + \frac{2}{3} + \frac{2}{3^{2} } + \frac{2}{3^{3}} + \frac{2}{3^{4}} + \frac{2}{3^{5}} + \frac{2}{3^{6}}[/tex]
here, we can see that every term is (1/3) times the last term
Hence, we can say that the common ratio of this Geometric Series is 1/3
Finding the Sum:
We know that the sum of a Geometric Series is:
[tex]S_{n} = \frac{a(r^{n}-1)}{r-1}[/tex]
(where r is the common ratio, a is the first term, and n is the number of terms)
another look at the given Geometric Series tells us that the first term is 2 and the number of terms is 7
plugging these values in the formula, we get:
[tex]S_{n} = \frac{2((1/3)^{7}-1)}{(1/3)-1}[/tex]
[tex]S_{n} = \frac{-1.99}{-0.67}[/tex]
Sₙ = 2.97
Step-by-step explanation:
[tex] \tt2 + \frac{2}{3} + \frac{2}{ {3}^{2} } + \frac{2}{ {3}^{3} } + \frac{2}{ {3}^{4} } + \frac{2}{ {3}^{5} } + \frac{2}{ {3}^{6} } [/tex]
r = [tex]\tt{a_2 \div a_1}[/tex]
r = [tex]\tt{\frac{2}{3} \div 2}[/tex]
r = [tex]\tt{\bold{\frac{1}{3}}}[/tex]
Soo :
[tex] \sf s_n = \frac{a( {r}^{n} - 1) }{r - 1} [/tex]
[tex] \sf s_7 = \frac{2(( \frac{1}{3} ) {}^{7 - 1} - 1) }{( \frac{1}{3} - 1) } [/tex]
[tex] \sf s_7 \approx \bold{ \underline{2.97}}[/tex]