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December 20, 2014

December 20, 2014

Posted by **Anonymous** on Sunday, February 21, 2010 at 4:42am.

- arithmetic -
**Reiny**, Sunday, February 21, 2010 at 7:36amAs usual, let the first term be a, and we know d = .5

S_{25}= 25/2[2a + 24(.5)] = 25a + 150

T_{25}= a + 24d = a + 12

given: S_{25}= (T_{25})^2

25a + 150 = (a+12)^2

a^2 + 24a + 144 = 25a + 150

a^2 - a - 6 = 0

(a-3)(a+2) = 0

a = 3 or a = -2

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