<span>(2,6-2,2:y):0,19-19/12=221/12
(0,4:у):0,19-1,583=18,416
0,4:у:0,19=18,416+1,583
</span>0,4:у:0,19=19,99
0,4:у=19,99*0,19
0,4:у=3,7981
у=3,7981*0,4
у=1,51924
1)22-2=20
Ответ:Вася пробежал стометровку за 20 секунд.
А+219=863-196
а+219=667
а=667-219
а=448
![6sin (\frac{23\pi}{4} )\cdot sin \frac{x}{2} +cosx=3\\\\\star \; \; sin \frac{23\pi}{4} =sin(6\pi -\frac{\pi}{4})=sin(-\frac{\pi}{4})=-sin\frac{\pi}{4}=-\frac{\sqrt2}{2}\; \; \; \star \\\\-3\sqrt2\cdot sin\frac{x}{2}+(1-2sin^2\frac{x}{2})-3=0\; ,\quad \star \; cos \alpha =1-2sin^2\frac{ \alpha }{2}\; \star \\\\2sin^2 \frac{x}{2}+3\sqrt2\cdot sin \frac{x}{2} }+2=0\\\\D=18-16=2\\\\(sin\frac{x}{2})_1= \frac{-3\sqrt2-\sqrt2}{4}=-\sqrt2\ \textless \ -1\; ,\; net\; reshenij](https://tex.z-dn.net/?f=6sin+%28%5Cfrac%7B23%5Cpi%7D%7B4%7D+%29%5Ccdot+sin+%5Cfrac%7Bx%7D%7B2%7D+%2Bcosx%3D3%5C%5C%5C%5C%5Cstar+%5C%3B+%5C%3B+sin+%5Cfrac%7B23%5Cpi%7D%7B4%7D+%3Dsin%286%5Cpi+-%5Cfrac%7B%5Cpi%7D%7B4%7D%29%3Dsin%28-%5Cfrac%7B%5Cpi%7D%7B4%7D%29%3D-sin%5Cfrac%7B%5Cpi%7D%7B4%7D%3D-%5Cfrac%7B%5Csqrt2%7D%7B2%7D%5C%3B+%5C%3B+%5C%3B+%5Cstar+%5C%5C%5C%5C-3%5Csqrt2%5Ccdot+sin%5Cfrac%7Bx%7D%7B2%7D%2B%281-2sin%5E2%5Cfrac%7Bx%7D%7B2%7D%29-3%3D0%5C%3B+%2C%5Cquad+%5Cstar+%5C%3B+cos+%5Calpha+%3D1-2sin%5E2%5Cfrac%7B+%5Calpha+%7D%7B2%7D%5C%3B+%5Cstar+%5C%5C%5C%5C2sin%5E2+%5Cfrac%7Bx%7D%7B2%7D%2B3%5Csqrt2%5Ccdot+sin+%5Cfrac%7Bx%7D%7B2%7D+%7D%2B2%3D0%5C%5C%5C%5CD%3D18-16%3D2%5C%5C%5C%5C%28sin%5Cfrac%7Bx%7D%7B2%7D%29_1%3D+%5Cfrac%7B-3%5Csqrt2-%5Csqrt2%7D%7B4%7D%3D-%5Csqrt2%5C+%5Ctextless+%5C+-1%5C%3B+%2C%5C%3B+net%5C%3B+reshenij)
![(sin\frac{x}{2})_2= \frac{-3\sqrt2+\sqrt2}{4} =-\frac{\sqrt2}{2}](https://tex.z-dn.net/?f=%28sin%5Cfrac%7Bx%7D%7B2%7D%29_2%3D++%5Cfrac%7B-3%5Csqrt2%2B%5Csqrt2%7D%7B4%7D+%3D-%5Cfrac%7B%5Csqrt2%7D%7B2%7D)
![\frac{x}{2}=(-1)^{n}(-\frac{\pi}{4})+\pi n=(-1)^{n+1}\frac{\pi}{4}+\pi n,\; n\in Z\\\\x=(-1)^{n+1}\frac{\pi}{2}+2\pi n,\; n\in Z](https://tex.z-dn.net/?f=%5Cfrac%7Bx%7D%7B2%7D%3D%28-1%29%5E%7Bn%7D%28-%5Cfrac%7B%5Cpi%7D%7B4%7D%29%2B%5Cpi+n%3D%28-1%29%5E%7Bn%2B1%7D%5Cfrac%7B%5Cpi%7D%7B4%7D%2B%5Cpi+n%2C%5C%3B+n%5Cin+Z%5C%5C%5C%5Cx%3D%28-1%29%5E%7Bn%2B1%7D%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+n%2C%5C%3B+n%5Cin+Z)
хЄ[-5;7,85] ⇒ x=-3П/2 ; -П/2 ; П/2 ; 3П/2 .
-5 радиан~ -286,5°
7,85 радиан ~ 449,8°
5*(810:9-2x)=40*8-5;
5(90-2х)=320-5; 5 умножаем на 90 и на -2х
450-10х=315;
-10=315-450;
-10=-135; |:(-10)
х=13.5
Ответ: х=13.5.
Проверено.