Ответ:
Объяснение:
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2a³+8a²-ab+c
a= - 3
2·(-3)³+8·(-3)²-(-3)b+c =2·(-27)+8·9+3b+c=-27+72+9b+c=3b + c + 18
a=2
2·2³+8·2²-2b+c =2·8+8·4-2b+c=16+32-2b+c=- 2b + c + 48
![\begin{cases}3b + c + 18=0\\- 2b + c + 48=0\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D3b+%2B+c+%2B+18%3D0%5C%5C-+2b+%2B+c+%2B+48%3D0%5Cend%7Bcases%7D+)
![\begin{cases}3b + c =- 18\\- 2b + c =-48\ /\cdot(-1)\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D3b+%2B+c+%3D-+18%5C%5C-+2b+%2B+c+%3D-48%5C+%2F%5Ccdot%28-1%29%5Cend%7Bcases%7D+)
![\begin{cases}3b + c =- 18\\2b - c =48\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D3b+%2B+c+%3D-+18%5C%5C2b+-+c+%3D48%5Cend%7Bcases%7D+)
+_______________
![5b=30\ /:5](https://tex.z-dn.net/?f=5b%3D30%5C+%2F%3A5)
![b=6](https://tex.z-dn.net/?f=b%3D6)
![\begin{cases} b=6\\ 3b + c =- 18\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D+b%3D6%5C%5C+3b+%2B+c+%3D-+18%5Cend%7Bcases%7D+)
![\begin{cases} b=6\\ 3 \cdot 6 + c =- 18\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D+b%3D6%5C%5C+3+%5Ccdot+6+%2B+c+%3D-+18%5Cend%7Bcases%7D+)
![\begin{cases} b=6\\ 18 + c =- 18\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D+b%3D6%5C%5C+18+%2B+c+%3D-+18%5Cend%7Bcases%7D+)
![\begin{cases} b=6\\ c =- 18-18\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D+b%3D6%5C%5C+c+%3D-+18-18%5Cend%7Bcases%7D+)
![\begin{cases} b=6\\ c =-36\end{cases}](https://tex.z-dn.net/?f=+%5Cbegin%7Bcases%7D+b%3D6%5C%5C+c+%3D-36%5Cend%7Bcases%7D+)
![b+c=6+(-36)=-30](https://tex.z-dn.net/?f=b%2Bc%3D6%2B%28-36%29%3D-30)
2)5x*(x⁴-5)+20x≥5x⁵-2
5x⁵-25x+20x≥5x⁵-2
-25x+20x≥-2
-5x≥-2
x≤0,4
Ответ xнаиб=0,4.
4)(2x-1)*(5-6x)-(3x+1)*(3-4x)≤3
16x-12x²-5-(5x-12x²+3)≤3
16x-12x²-5-5x+12x²-3≤3
11x≤11
x≤1
Ответ:xнаиб=1
Область определения логарифмической функции при разных значениях основания — все положительные числа: D(y) = (0; +∞).<span> Область значений — все действительные числа: E(y) = ( -</span>∞<span>; +</span>∞<span>).
Поэтому выражение 72 - 2х</span>² > 0
2x² < 72
x² < 36
-6 < x < +6
Отсюда -6 < x < 6.