Упростим левую часть:
![\left( \cfrac{\cos \beta }{\sin \alpha }+ \cfrac{\sin \beta }{\cos \alpha } \right) \cdot\sin2 \alpha =\\\\\\= \cfrac{\cos \alpha \cos \beta+ \sin \alpha \sin \beta }{\sin \alpha \cos \alpha } \cdot\ 2\sin \alpha \cos \alpha =\cos( \alpha - \beta ) \cdot2=2\cos( \alpha - \beta )](https://tex.z-dn.net/?f=%5Cleft%28+%5Ccfrac%7B%5Ccos++%5Cbeta++%7D%7B%5Csin++%5Calpha++%7D%2B++%5Ccfrac%7B%5Csin++%5Cbeta++%7D%7B%5Ccos++%5Calpha++%7D+%5Cright%29+%5Ccdot%5Csin2+%5Calpha+%3D%5C%5C%5C%5C%5C%5C%3D+%5Ccfrac%7B%5Ccos++%5Calpha++%5Ccos++%5Cbeta%2B+%5Csin+%5Calpha++%5Csin+%5Cbeta++%7D%7B%5Csin++%5Calpha+%5Ccos+%5Calpha+++%7D+%5Ccdot%5C+2%5Csin+%5Calpha+%5Ccos+%5Calpha++%3D%5Ccos%28+%5Calpha+-+%5Cbeta+%29+%5Ccdot2%3D2%5Ccos%28+%5Calpha+-+%5Cbeta+%29)
Левая часть равна правой. Тождество доказано.
<span>х <span>n+6</span> = x4. n+6=4. n = 4-6 , n=-2; 2) х3-<span>n </span>= x -2, 3-n = -2, n = 3+2,
n = 5; 3) x -3*n * x3 = x6, -3n+3=6, -3n=3, n=-1; 4)x(-<span>n)*(-4)</span> = x -4, 4n=-4, n=-1.</span>
43 - 2* 3√3 * 4 = (3√3)^2 - 2 * 3√3 * 4 + 4^2 = (3√3 - 4)^2
3√3 > 4 след. опускаем корень и квадрат
получится просто 3√3 - 4
<span>х^2 - x + 9 = (x + 2)^2
</span><span>х^2 - x + 9 = x^2 + 4x + 4
</span><span>х^2 - x + 9 - x^2 - 4x - 4 </span>= 0
- 5x = - 5
x = 1