![5-2x=11-7(x+2)](https://tex.z-dn.net/?f=5-2x%3D11-7%28x%2B2%29)
![5-2x=11-7x-14](https://tex.z-dn.net/?f=5-2x%3D11-7x-14)
![5-2x=-3-7x](https://tex.z-dn.net/?f=5-2x%3D-3-7x)
![7x-2x=-3-5](https://tex.z-dn.net/?f=7x-2x%3D-3-5)
![5x=-8](https://tex.z-dn.net/?f=5x%3D-8)
![x=-8:5](https://tex.z-dn.net/?f=x%3D-8%3A5)
![x=-\frac{8}{5}=-1,6](https://tex.z-dn.net/?f=x%3D-%5Cfrac%7B8%7D%7B5%7D%3D-1%2C6)
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(это проверка)
![5+3,2=11-7\cdot0,4](https://tex.z-dn.net/?f=5%2B3%2C2%3D11-7%5Ccdot0%2C4)
![8,2=11-2,8](https://tex.z-dn.net/?f=8%2C2%3D11-2%2C8)
![8,2=8,2](https://tex.z-dn.net/?f=8%2C2%3D8%2C2)
1)x^2-9-x^2-4x=0
-4x=9
x=9/(-4)
x=-2,25
2)3x+36x^2-(36x^2-1)=2,5x
3x+36^2-36^2+1=2,5x
3x-2,5x=-1
0,5x=-1
x=-1/0,5
x=-2
Сперва выполняется умножение
![\frac{a}{a^2-c^2}* \frac{a+c}{2ac}= \frac{a}{(a-c)(a+c)}* \frac{a+c}{2ac}= \frac{a(a+c)}{(a-c)(a+c)*2ac}= \frac{1}{2c(a-c)}](https://tex.z-dn.net/?f=+%5Cfrac%7Ba%7D%7Ba%5E2-c%5E2%7D%2A+%5Cfrac%7Ba%2Bc%7D%7B2ac%7D%3D+%5Cfrac%7Ba%7D%7B%28a-c%29%28a%2Bc%29%7D%2A+%5Cfrac%7Ba%2Bc%7D%7B2ac%7D%3D+%5Cfrac%7Ba%28a%2Bc%29%7D%7B%28a-c%29%28a%2Bc%29%2A2ac%7D%3D+%5Cfrac%7B1%7D%7B2c%28a-c%29%7D+++)
теперь деление:
![\frac{1}{2c(a-c)}: \frac{1}{a-c}=\frac{1}{2c(a-c)}* \frac{a-c}{1}=\frac{1*(a-c)}{2c(a-c)}= \frac{1}{2c}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2c%28a-c%29%7D%3A+%5Cfrac%7B1%7D%7Ba-c%7D%3D%5Cfrac%7B1%7D%7B2c%28a-c%29%7D%2A+%5Cfrac%7Ba-c%7D%7B1%7D%3D%5Cfrac%7B1%2A%28a-c%29%7D%7B2c%28a-c%29%7D%3D+%5Cfrac%7B1%7D%7B2c%7D++)
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