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Geometric q

Uhhh yeah the question was obvious however I think Ive stumbled on something interesting
(edited 9 years ago)
Is that 2 multiplied by 5^n?


Posted from TSR Mobile
We take the first term as n=1 rather than 0, that's where the 10 is coming from, and then just whack 5 in for the 5th term.


Posted from TSR Mobile
The answer is obvious.
But if it is geometric and the nth term is 2 x (5)^n
Then ar^n-1= 2 x (5)^n
(Correct me if I'm wrong) Then you can say since 2 does not square to 5 then r^n-1 =5^n
then you can say r^n= 5^n x r
(For the 5th term) If r is really 5 then you can say 5^5=5^5 x 5
I've tried to find my mistake but I cannot see it (if its really there)
Is this because the sequence goes a, ar, ar^2, ar^3....??
Or somebody plz spot my probably obvious error

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