(4у-4х = - 9
(4 у +х = 2 | - 1
(4у - 4х = - 9
( -4у - х = -2 (4у и -4у сокращаются )
- 5х = - 11
х = 2, 2.( подставляем значение х )
4 у+ х = 2
4 у+2, 2= 2
4 у = 2 - 2,2
у =- 0,2 : 4
у = -0, 05
Ответ: х=2,2; у= - 0,05
![bc+b^{2}-3c-3b](https://tex.z-dn.net/?f=bc%2Bb%5E%7B2%7D-3c-3b)
для начала упростим данное выражение
![bc+b^{2}-3c-3b=(bc+b^{2})+(-3c-3b)=(bc+b^{2})-(3c+3b)=(bc+b^{2})-(3b+3c)=b(c+b)-3(b+c)=(b+c)(b-3)](https://tex.z-dn.net/?f=bc%2Bb%5E%7B2%7D-3c-3b%3D%28bc%2Bb%5E%7B2%7D%29%2B%28-3c-3b%29%3D%28bc%2Bb%5E%7B2%7D%29-%283c%2B3b%29%3D%28bc%2Bb%5E%7B2%7D%29-%283b%2B3c%29%3Db%28c%2Bb%29-3%28b%2Bc%29%3D%28b%2Bc%29%28b-3%29)
при b=3,7; с=-4,7
![(3,7+(-4,7))(3,7-3)=(3,7-4,7)(3,7-3)=-1\cdot0,7=-0,7](https://tex.z-dn.net/?f=%283%2C7%2B%28-4%2C7%29%29%283%2C7-3%29%3D%283%2C7-4%2C7%29%283%2C7-3%29%3D-1%5Ccdot0%2C7%3D-0%2C7)
(3/2-2/3)х=30
5х/6=30
х=180/5
<span>х=36</span>
8n^2(mn-3)-7(mn-3)=(8n^2-7)(mn-3)
(5m^2n+10m^2)-(6an+3an^2)=(5m^2(n+2))-(3an(2+n))=(5m^2-3an)(n+2)