What's the formula for Geometric progression?

Answer 1

A geometric progression is a series or sequence in which each element is a constant ratio of its predecessor.
So the nth term of a geometric progression is a_n = a_0 x r^(n-1).
Is this what you need? Or do you need the formula for the sum of a geometric progression, or some related formula? For more formulas and info related to geometric progressions see...
http://en.wikipedia.org/wiki/Geometric_progression

Answer 2

in this expression: sn=a+ ar+ ar^2 + ar^3 ... ar^n-a million= a(a million + r + r^2 + r^3 +... + r^n-a million) the ... means there would desire to be words in between the ar^3 and the final term of the sequence. ar^(n-a million) means that the exponent on the r is one under the # of words interior the sequence. to illustrate, in case you prefer to locate the sum of the 1st 10 words, you will multiply a * r^9 for the final term. once you multiply the completed equation via r on the two aspects, you're multipliying the final term to get a*r^(n-a million)*r which equals a*r^n. {bear in mind, you upload exponents once you multiply}

Answer 3

Let first term = a (common ratio r)
2nd term = a r
3 rd term = a r²
4th term = a r³
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nth term = a r^(n-1)