Please help, the sooner the better :)
57
What is the sum of the geometric series?
-.- very funny
LOL!
\(\large { \textit{sum of geometric sequence}=S{\color{brown}{ n}}=a_1\left( \cfrac{1-r^{\color{brown}{ n}}}{1-r} \right)\qquad\\ \quad \\ \Sigma_{n=1}^{10}\quad 6(2)^{\color{brown}{ n}} \\ \quad \\ a_1\to \textit{first term of sequence} }\)
oh dear, many numbers and letters... ok...
so in this case since n = 10 then \(\bf S_{\color{brown}{ 10}}=a_1\left( \cfrac{1-r^{\color{brown}{ 10}}}{1-r} \right)\)
oh ok that makes a bit of sense
so am I trying to figure out what S is?
ohh S is jus the notation for "S"um
I'm already confused :(
another way of saying if we have "n" terms, beginning at \(a_1\) the "S"um of it will be this
oh ok, then why does it have base 10?
it is not a base yes, it looks like that because is a subscript of the letter is just a way to say "a sum that goes up to "n"th number"
ah ok
hmmm actually we haven't plugged in "r" one sec
ok
I have to go, please continue to explain and I will read it when I come back
\(\large { \bf \textit{sum of geometric sequence}=S_{\color{brown}{ n}}=a_1\left( \cfrac{1-{\color{blue}{ r}}^{\color{brown}{ n}}}{1-{\color{blue}{ r}}} \right) \\ \quad \\ \qquad a_1\to \textit{first term of the sequence} \\ \quad \\ \Sigma_{{\color{brown}{ n}}=1}^{10}\quad 6({\color{blue}{ 2}})^{\color{brown}{ n}}\implies S_{\color{brown}{ 10}}=a_1\left( \cfrac{1-{\color{blue}{ 2}}^{\color{brown}{ 10}}}{1-{\color{blue}{ 2}}} \right) }\)
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