![1+\sin \leftx\right+\cos \leftx\right+\sin \left2x\right+\cos \left2x\right=0 \\ 1+\cos \left2x\right+\cos \leftx\right+\sin \leftx\right+2\cos x\leftx\right\sin x\leftx\right=0 \\ \cos \left x\right +\sin \left x\right+2\cos ^2\leftx\right+2\cos \left x\right\sinx \leftx\right=0 \\ \left(2\cos \left(x\right)+1\right)\left(\sin \left(x\right)+\cos \left(x\right)\right)=0](https://tex.z-dn.net/?f=1%2B%5Csin+%5Cleftx%5Cright%2B%5Ccos+%5Cleftx%5Cright%2B%5Csin+%5Cleft2x%5Cright%2B%5Ccos+%5Cleft2x%5Cright%3D0+%5C%5C+1%2B%5Ccos+%5Cleft2x%5Cright%2B%5Ccos+%5Cleftx%5Cright%2B%5Csin+%5Cleftx%5Cright%2B2%5Ccos+x%5Cleftx%5Cright%5Csin+x%5Cleftx%5Cright%3D0+%5C%5C+%5Ccos+%5Cleft+x%5Cright+%2B%5Csin+%5Cleft+x%5Cright%2B2%5Ccos+%5E2%5Cleftx%5Cright%2B2%5Ccos+%5Cleft+x%5Cright%5Csinx+%5Cleftx%5Cright%3D0+%5C%5C+%5Cleft%282%5Ccos+%5Cleft%28x%5Cright%29%2B1%5Cright%29%5Cleft%28%5Csin+%5Cleft%28x%5Cright%29%2B%5Ccos+%5Cleft%28x%5Cright%29%5Cright%29%3D0)
2cos(x)+1=0 sin(x)+cos(x)=0
cos(x)= - 1/2
![\cos \left(x\right)=-\frac{1}{2} ;x=\frac{2\pi }{3}+2\pi n,\:\quad x=\frac{4\pi }{3}+2\pi n \\ sin(x)+cos(x)=0;\quad x=\frac{3\pi }{4}+\pi n](https://tex.z-dn.net/?f=%5Ccos+%5Cleft%28x%5Cright%29%3D-%5Cfrac%7B1%7D%7B2%7D+%3Bx%3D%5Cfrac%7B2%5Cpi+%7D%7B3%7D%2B2%5Cpi+n%2C%5C%3A%5Cquad+x%3D%5Cfrac%7B4%5Cpi+%7D%7B3%7D%2B2%5Cpi+n+%5C%5C+++sin%28x%29%2Bcos%28x%29%3D0%3B%5Cquad+x%3D%5Cfrac%7B3%5Cpi+%7D%7B4%7D%2B%5Cpi+n)
![Otvet:x=\frac{2\pi }{3}+2\pi n,\:x=\frac{3\pi }{4}+\pi n,\:x=\frac{4\pi }{3}+2\pi n](https://tex.z-dn.net/?f=Otvet%3Ax%3D%5Cfrac%7B2%5Cpi+%7D%7B3%7D%2B2%5Cpi+n%2C%5C%3Ax%3D%5Cfrac%7B3%5Cpi+%7D%7B4%7D%2B%5Cpi+n%2C%5C%3Ax%3D%5Cfrac%7B4%5Cpi+%7D%7B3%7D%2B2%5Cpi+n)
S=V*t, t=S/v, t=S/(V1+V2), t=13,5/(5+4)=1,5, через 1,5 (полтора часа) они встретятся.
3а-10-9а+4=(3а-9а)+(-10+4)=-6а-6
f(x)=-1/3x^3+4x+3Пусть x1>x2 ,тогда:(x1)^3>(x2)^3-1/3*(x1)^3<-1/3*(x2)^3-1/3*(x1)^3+x<-1/3*(x2)^3+x-1/3*(x1)^3+4x<-1/3*(x2)^3+4x-1/3*(x1)^3+4x+3<-1/3*(x2)^3+4x+3<span>Т.к. y1<y2 ,то функция:f(x)=-1/3x^3+4x+3 - убывает на промежутек:(-∞;∞)</span>