- 35 + 5х > 0
6 - 3х > - 18
Решение
5х > 35
3х < 6 + 18
-----
Х > 7
Х < 8
Ответ ( 7 ; 8 )
X(x+2)-3 = 4 (x+1)-1
x^2+ 2x - 3 = 4x + 4 - 1
x^2 + 2x - 4x = 3 + 4 -1
x^2 - 2x = 6
x^2 - 2x - 6 = 0
x1+x2 = 2
x1 * X2 = -6
X1 = -3
X2 = 2
не помню, вроди так
![\left \{ {{b1+b3=30} \atop {b2+b4=90}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7Bb1%2Bb3%3D30%7D+%5Catop+%7Bb2%2Bb4%3D90%7D%7D+%5Cright.+)
⇒
![\left \{ {{b1+b1q ^{2} =30} \atop {b1q+b1q^3=90}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7Bb1%2Bb1q+%5E%7B2%7D+%3D30%7D+%5Catop+%7Bb1q%2Bb1q%5E3%3D90%7D%7D+%5Cright.+)
![\left \{ {{b1(1+q^2)=30} \atop {b1q(1+q^2)=90}} \right.](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7Bb1%281%2Bq%5E2%29%3D30%7D+%5Catop+%7Bb1q%281%2Bq%5E2%29%3D90%7D%7D+%5Cright.+)
1+q²=30/b₁; ⇒b1·q·30/b1=90; ⇒q=9/30=3;
b1=30/(1+q²)=30/(1+9)=30/10=3;