Hi All,

I need a hint for this one. I think I may be missing something here.

Find the first term and common ratio if,

Thanks for your help!

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- April 10th 2011, 11:53 PMmathguy80Find first term and common ratio of Geometric progression
Hi All,

I need a hint for this one. I think I may be missing something here.

Find the first term and common ratio if,

Thanks for your help! - April 11th 2011, 12:19 AMveileen
Who are ? Write their formula using the first term (let's say ) and the ration (q), then you'll have a system of equations in two unknowns.

- April 11th 2011, 05:07 AMSambit
I suppose are, respectively, the sum of first 5,9 and 10 terms--right?

If this is the case and first term= , ratio= , then the sum of the GP series upto first terms will be

So your first equation reduces to and second equation reduces to

Solve these two equations to get and . - April 11th 2011, 09:44 AMbjhoppergeometric progressions
Hi mathguy80,

Sambits first equation can be simplified to produce a quadratic equation in one unknown (r) SUbstitute r in the second to find a.

bjh - April 11th 2011, 10:44 PMmathguy80
Thanks guys, That clears things up. The quadratic equation was the key. I was a little confused by the large power and thought I wouldn't be able to factorize. Substituting, made it into a simple quadratic to solve! :)