Ответы и объяснения

2014-02-28T10:03:39+00:00
B1 = √3; q = -1/√3
S5 = b1 * (1-qn)/(1-q) =  √3 * (1 - (-1/√3)5)/( 1 - (-1/√3)) = √3 * (1 + 1/(9√3) ) / (1+1/√3) =
= (√3 + 1/9 ) / (1+1/√3) = (9√3+1)/9 : (√3+1)/√3 =
= (9√3+1)/(√3+1) * √3 /9 = (9√3+1)*(√3-1)/2 * √3 /9 =
= (27-9√3 +√3 -1) * √3 /18 =
= (26-8√3) * √3 /18 = (26√3-24)/18 =
= (13√3-12)/9