Умножаем 2 уравнение на -2 и складываем:
-8x-10y+8x+2y=11-22;
-8y=-11; y=11/8;
8x+2,75=11;
8x=8,25;
x=825/800=33/32;
Ответ: (33/32; 11/8)
![x^2-1\geq 0\\ x^2\geq 1\\ |x|\geq 1](https://tex.z-dn.net/?f=+x%5E2-1%5Cgeq+0%5C%5C+x%5E2%5Cgeq+1%5C%5C+%7Cx%7C%5Cgeq+1+)
Последнее неравенство эквивалентно совокупности неравенств
![\left[\begin{array}{ccc}x\geq 1\\ x\leq -1\end{array}\right](https://tex.z-dn.net/?f=+%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Dx%5Cgeq+1%5C%5C+x%5Cleq+-1%5Cend%7Barray%7D%5Cright+)
Ответ: ![x \in (-\infty;-1]\cup[1;+\infty).](https://tex.z-dn.net/?f=+x+%5Cin+%28-%5Cinfty%3B-1%5D%5Ccup%5B1%3B%2B%5Cinfty%29.+)
(3х-5у)-(3х+5у)=3x-5y-3x-5y=-10y
...............................................................................
58(одноклассников)--------100%
17(одноклассников)--------x%
![x= \frac{17*100}{58}= \frac{1700}{58}=29.3](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B17%2A100%7D%7B58%7D%3D+%5Cfrac%7B1700%7D%7B58%7D%3D29.3++)
Ответ: ≈29,3%