Решение уравнения при х=9, тогда √9=3=6-9/3. График во вложении.
B₆ = √b₅*b₇ = 15
У нас ряд: ...; 25; 15; 9;...
q = 9/15 = 3/5
b₅ = b₁q⁴
25 = b₁*(3/5)⁴
b₁ = 25 : 625/81= 25*81/625 = 81/25
S₆ = 81/25*((3/5)⁶ -1)/(1 - 3/5) = 81*7448/15625
Вооот, ответы, я чуть не сдох
B10 = b1*q^9
b8 = b1*q^7
b10/b8 = b1*q^9/<span>b1*q^7 = q^2 = 9 => q = 3
b3 = b1*q^2
b6 = b1*q^5
b3 + b6 = </span>b1*q^2 + <span>b1*q^5 = b1(q^2 + q^5) = 168 => b1 = 168 / (q^2 +q^5) =
=168 / (3^2 + 3^5) = 168 / (9 + 243) = 168 / 252 = 2/3</span>