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# g1=2, gn+1 = 3gn, what is g4-g2?

in the geometric series where g subscript 1 =2 and g subscript (n+1) = 3g subscript n, what is g subscript 4 minus g subscript 2

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### 3 Answers

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- hayharbrLv 71 decade agoFavorite Answer
So it goes: 2, 6, 18, 54, ... because each term is multiplied by 3 to get the next term. g4 is 54 and g2 is 6 so g4 - g2 is 48

- 1 decade ago
I'm using [ ] to show subscripts

g[1] = 2

g[n+1] = 3g[n]

Therefore we can find g[2], seeing that we know g[1]

g[1+1] = 3g[1]

g[2] = 3g[1] = 3*2 = 6

Now we have to find g[4], but we must find g[3] in order to do that.

g[3] = 3g[2] = 3*6 = 18

g[4] = 3g[3] = 3*18 = 54

therefore: g[4] - g[2] = 54 - 6 = 48

That's your answer!

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