Question

b1=-2 q=3/4 Найти: Sn

Answer 1

$Sn = frac{b1( {q}^{n} - 1) }{q - 1} = frac{ - 2( {( frac{3}{4}) }^{n} - 1) }{ frac{3}{4} - 1 } = frac{ - 2( frac{ {3}^{n} }{ {4}^{n} } - 1) }{ - frac{1}{4} } = 8( frac{ {3}^{n} }{ {4}^{n} } - 1)$