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Geometric Series Help! Algebra 2!?

0 votes
I need help solving these types of geometric series questions. all they give me is..
A1= -4 r= 4 and Sn= -5460
they tell me to find n.
i have to use the formula
Sn=A1(1-r^n) over 1-r
asked May 16, 2013 in ALGEBRA 2 by mathgirl Apprentice

1 Answer

+1 vote

Given that A₁ = - 4, r = 4, Sn = - 5460

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Substitute A₁ = - 4, r = 4, Sn = - 5460 in the equation

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Multiply each side by negative one

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Divide each side by 4

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Multiply each side by -3

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Subtract 1 from each side

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Multiply each side by negative one

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Therefore n = 6.

answered May 17, 2013 by richardson Scholar

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