Problem 13 of 7
Find the sum of the finite geometric series with first term 3, ratio 2, and 6 terms.
Hints
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use S_n=a(1-r^n)/(1-r).
Hidden until you reveal it.
Use S_n=a(1-r^n)/(1-r) when r!=1.
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Solution
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1. Identify a, r, and n.
2. If r!=1, substitute into S_n=a(1-r^n)/(1-r).
3. If r=1, multiply a by n.
4. Interpret the finite sum in context if one is given.
Use the worked steps, then substitute the final answer back into the original relationship to confirm it satisfies the prompt.
Applying the r!=1 formula blindly when r=1.