1) y^3+21*y^2+147*y+343-y^3-21*y^2>0
147y+343>0
147y>-343
y>-2.(3)
2)216-54y+18y^2-y^3+y^3-18y^2<0
216-54y<0
54y>216
y>4
Х=5 - вертикальная прямая
у=5 - горизонтальная прямая
<span>4ab+2(a-b)²=
4ab+2(a²-2ab+b²)=
4ab+2a²-4ab+2b²=
2a²+2b²</span>
2x+3y = -11
2x-3y = 7
2x+3y+2x-3y = -11 + 7
2x + 2x = -4
4x = -4
x = -1
2*-1 - 3y = -11
-2 - 3y = -11
-3y = -11 + 2
-3y = -9
y = 3
Вот......................