- #1
NotaPhysicist
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Homework Statement
Find the first three terms of a geometric sequence given that the sum of the first four terms is 65/3 and the sum to infinity is 27.
Homework Equations
[tex]
\begin{array}{1}
S_n = \frac{a(1 - r^n)}{1 - r}\\
S_n = \frac{a(r^n - 1}{r - 1}
\end{array}
[/tex]
The Attempt at a Solution
I'm trying to get two equations in two unknowns.
I end with
a + 27r = 27
But I get lost after that. Trying to solve the sum leaves me with a equation to fourth or fifth power which I can't solve.
I'm sure there's a simple approach to this.
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