1. S=224 м²
S=ab
а-большая сторана
b-меньшая сторона
a - x+2
b - x
Уравнение:
х(х+2)=224
х²+2х-224=0
D=900=30²
x=14 (меньшая сторона)
14+2=16 (большая сторона)
2. Найдем периметр:
P=2(a+b)
P=2(14+16)=60
60/5=12 упаковок надо купить
Фи. Уравнения не хотят вставляться.
Ладно. По-другому.
183.
a)![f(x)=x^3-3x^2+7x\\f`(x)=3x^2-6x+7\\f`(x)=0\\3x^2-6x+7=0\\D=(-6)^2-4*3*7=36-84=-48<0](https://tex.z-dn.net/?f=f%28x%29%3Dx%5E3-3x%5E2%2B7x%5C%5Cf%60%28x%29%3D3x%5E2-6x%2B7%5C%5Cf%60%28x%29%3D0%5C%5C3x%5E2-6x%2B7%3D0%5C%5CD%3D%28-6%29%5E2-4%2A3%2A7%3D36-84%3D-48%3C0)
решений нет
б)![f(x)=3x^3-2x^2-1\\f`(x)=9x^2-4x=x(9x-4)\\f`(x)=0\\x(9x-4)=0](https://tex.z-dn.net/?f=f%28x%29%3D3x%5E3-2x%5E2-1%5C%5Cf%60%28x%29%3D9x%5E2-4x%3Dx%289x-4%29%5C%5Cf%60%28x%29%3D0%5C%5Cx%289x-4%29%3D0)
или ![9x-4=0](https://tex.z-dn.net/?f=9x-4%3D0)
![9x=4](https://tex.z-dn.net/?f=9x%3D4)
![x=4/9](https://tex.z-dn.net/?f=x%3D4%2F9)
184.
![f(x)=\frac{1}{3}x^3+4x^2-9x+1\\f`(x)=x^2+8x-9\\f`(x)>0\\x^2+8x-9>0\\(x+9)(x-1)>0](https://tex.z-dn.net/?f=f%28x%29%3D%5Cfrac%7B1%7D%7B3%7Dx%5E3%2B4x%5E2-9x%2B1%5C%5Cf%60%28x%29%3Dx%5E2%2B8x-9%5C%5Cf%60%28x%29%3E0%5C%5Cx%5E2%2B8x-9%3E0%5C%5C%28x%2B9%29%28x-1%29%3E0)
+ - +
____________ -9 ____________________ 1 _________________
![x\in(-\infty;-9)\cup(1;+\infty)](https://tex.z-dn.net/?f=x%5Cin%28-%5Cinfty%3B-9%29%5Ccup%281%3B%2B%5Cinfty%29)
![f(x)=-\frac{1}{3}x^3+x^2+3x\\f`(x)=-x^2+2x+3\\f`(x)>0\\-x^2+2x+3>0\\x^2-2x-3<0\\(x+1)(x-3)<0](https://tex.z-dn.net/?f=f%28x%29%3D-%5Cfrac%7B1%7D%7B3%7Dx%5E3%2Bx%5E2%2B3x%5C%5Cf%60%28x%29%3D-x%5E2%2B2x%2B3%5C%5Cf%60%28x%29%3E0%5C%5C-x%5E2%2B2x%2B3%3E0%5C%5Cx%5E2-2x-3%3C0%5C%5C%28x%2B1%29%28x-3%29%3C0)
+ _ +
________________ -1 _______________ 3 _____________________
![x\in(-1;3)](https://tex.z-dn.net/?f=x%5Cin%28-1%3B3%29)
!!!!!!!!!!!!!!!!!!!!!!!!!