Ответ:х•7х=21•2х
Объяснение:7х=42х х=42/7,х=6, проверка 6•7•6=21•2•6,252=252
(х-3)(Х^2+3х+9)=х(х-8)(х+9)
1)(1+30)30/2=465
(Натуральных значит с 1)
1) подставим:
(-2)²-(-2)+2=-2-6
4+2+2=-8
8=-8
ответ: нет
2)a)
![\frac{1}{3}*x= \frac{1}{2}](https://tex.z-dn.net/?f=+%5Cfrac%7B1%7D%7B3%7D%2Ax%3D+%5Cfrac%7B1%7D%7B2%7D++)
![x= \frac{1}{2}: \frac{1}{3}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B1%7D%7B2%7D%3A+%5Cfrac%7B1%7D%7B3%7D++)
![x= \frac{1}{2}* \frac{3}{1}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B1%7D%7B2%7D%2A+%5Cfrac%7B3%7D%7B1%7D++)
![x= \frac{3}{2}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B3%7D%7B2%7D+)
![x=1 \frac{1}{2}](https://tex.z-dn.net/?f=x%3D1+%5Cfrac%7B1%7D%7B2%7D+)
б) 7-2х=0
2х=7
![x= \frac{7}{2}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B7%7D%7B2%7D+)
x=
![x=3 \frac{1}{2}](https://tex.z-dn.net/?f=x%3D3+%5Cfrac%7B1%7D%7B2%7D+)
в)5-4х=х-1,5
х+4х=5+1,5
5х=6,5
х=6,5:5
х=1,3
г)х+2(3х-2)=10
х+6х-4=10
х+6х=10+4
7х=14
х=14:7
х=2
3) пусть цыпленку - х дней, тогда утенку - 2х дней, а гусенку - 3х дней.
а)х+2х+3х=120
6х=120
х=120:6
х=20 (дней) - цыпленку
б) 2*20=40 (дней) -утенку
в) 3*20=60 (дней) - гусенку
4)
![\frac{2}{3}(7-2x)= \frac{1}{2}](https://tex.z-dn.net/?f=+%5Cfrac%7B2%7D%7B3%7D%287-2x%29%3D+%5Cfrac%7B1%7D%7B2%7D++)
![7-2x= \frac{1}{2}: \frac{2}{3}](https://tex.z-dn.net/?f=7-2x%3D+%5Cfrac%7B1%7D%7B2%7D%3A+%5Cfrac%7B2%7D%7B3%7D++)
![7-2x= \frac{1}{2}* \frac{3}{2}](https://tex.z-dn.net/?f=7-2x%3D+%5Cfrac%7B1%7D%7B2%7D%2A+%5Cfrac%7B3%7D%7B2%7D++)
![7-2x= \frac{3}{4}](https://tex.z-dn.net/?f=7-2x%3D+%5Cfrac%7B3%7D%7B4%7D+)
![2x=7- \frac{3}{4}](https://tex.z-dn.net/?f=2x%3D7-+%5Cfrac%7B3%7D%7B4%7D+)
![2x= \frac{28-3}{4}](https://tex.z-dn.net/?f=2x%3D+%5Cfrac%7B28-3%7D%7B4%7D+)
![2x= \frac{25}{4}](https://tex.z-dn.net/?f=2x%3D+%5Cfrac%7B25%7D%7B4%7D+)
![x= \frac{25}{4}:2](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B25%7D%7B4%7D%3A2+)
![x= \frac{25}{4}* \frac{1}{2}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B25%7D%7B4%7D%2A+%5Cfrac%7B1%7D%7B2%7D++)
![x= \frac{25}{8}](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B25%7D%7B8%7D+)
![x=3 \frac{1}{8}](https://tex.z-dn.net/?f=x%3D3+%5Cfrac%7B1%7D%7B8%7D+)
x=3.125
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