3 кв . корень из 3
Ибо раскладываем под корнем на 9•3 потом вычисляем корень из 9
0.2 = 2/10 = 1/5 = 5^(-1)
5^(-1*10) * 5^10 = 5^0 = 1
или иначе: ... = (0.2 * 5)^10 = 1^10 = 1
![b_5=b_1*(\frac{1}{2})^4=\frac{1}{8}](https://tex.z-dn.net/?f=b_5%3Db_1%2A%28%5Cfrac%7B1%7D%7B2%7D%29%5E4%3D%5Cfrac%7B1%7D%7B8%7D)
![b_1*\frac{1}{16}=\frac{1}{8}](https://tex.z-dn.net/?f=b_1%2A%5Cfrac%7B1%7D%7B16%7D%3D%5Cfrac%7B1%7D%7B8%7D+)
![b_1=2](https://tex.z-dn.net/?f=b_1%3D2)
![S_3=\frac{2(\frac{1}{2})^3-1)}{\frac{1}{2}-1}=\frac{2(\frac{1}{8}-1)}{-\frac{1}{2}}=-4*(-\frac{7}{8})=\frac{7}{2}=3,5](https://tex.z-dn.net/?f=S_3%3D%5Cfrac%7B2%28%5Cfrac%7B1%7D%7B2%7D%29%5E3-1%29%7D%7B%5Cfrac%7B1%7D%7B2%7D-1%7D%3D%5Cfrac%7B2%28%5Cfrac%7B1%7D%7B8%7D-1%29%7D%7B-%5Cfrac%7B1%7D%7B2%7D%7D%3D-4%2A%28-%5Cfrac%7B7%7D%7B8%7D%29%3D%5Cfrac%7B7%7D%7B2%7D%3D3%2C5)
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7(-3+2х)=-6х-1
-21+14х=-6х-1
14х+6х=-1+21
20х=20
х=1