По свойству геометрической прогрессии
, тогда
![b_{3}=b_{1}*q^{2}=-\frac{1}{2}*(\frac{1}{2} )^{2} = -\frac{1}{8}](https://tex.z-dn.net/?f=b_%7B3%7D%3Db_%7B1%7D%2Aq%5E%7B2%7D%3D-%5Cfrac%7B1%7D%7B2%7D%2A%28%5Cfrac%7B1%7D%7B2%7D+%29%5E%7B2%7D+%3D+-%5Cfrac%7B1%7D%7B8%7D)
Ответ: ![-\frac{1}{8}](https://tex.z-dn.net/?f=-%5Cfrac%7B1%7D%7B8%7D)
(10+12+11+10+15+16):6=74:6~=12
Решение во вложении
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4|3x+1|+3|3x+1|>=-7x
7|3x+1|>=-7x
|3x+1|>=-x
3x>=-1 x>=-1/3
3x+1>=-x 4x>=-1 x>=-1/4
x<-1/3
-3x-1>=-x 2x<=-1 x<=-1/2
x<=-1/2 U x>=-1/4
(-∞;-1/2] U {-1/4;∞)