1, sin2x=1 2x=п/2+2Пk x=П/4+Пk k=-1 x=П/4-П=-3/4П
2. S=9*П*9/П=81
3. находим минимум y(-3/2)=9/4-5-9/2=-7,25
ответ -7
( 1000 - 1,6 ) : 31,2 = 998,4 : 31,2 = 32 ( литра )
![\frac{x+3}{ x^{2} -4} \leq 0](https://tex.z-dn.net/?f=%20%5Cfrac%7Bx%2B3%7D%7B%20x%5E%7B2%7D%20-4%7D%20%20%5Cleq%200)
![\frac{x+3}{ (x-2)(x+2)} \leq 0](https://tex.z-dn.net/?f=%20%5Cfrac%7Bx%2B3%7D%7B%20%28x-2%29%28x%2B2%29%7D%20%20%5Cleq%200)
- + - +
--------------------[-3]-----------(-2)-----------(2)-----------------
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Ответ:
![(-](https://tex.z-dn.net/?f=%28-)
∞
![; -3]](https://tex.z-dn.net/?f=%3B%20-3%5D)
∪
![(-2;2)](https://tex.z-dn.net/?f=%28-2%3B2%29)
-2х-10=7х^2-10
7х^2-10+2х+10=0
7х^2+2х=0
Х(7х+2)=0
Х=0 или 7х+2=0
7х=-2
Х=-2/7