Х^2 - 6х + с = 0
Х = - 2
( - 2 )^2 - 6•( - 2 ) + с = 0
4 + 12 + с = 0
с = - 16
----------
Х^2 - 6х - 16 = 0
D = 36 + 64 = 100 = 10^2
X1 = ( 6 + 10 ) : 2 = 8
X2 = ( 6 - 10 ) : 2 = - 2
Ответ ( - 16 ) ; 8
4*(1+cos2x)²/4 -1 =cos2x
(1+cos2x)² -(1+cos2x)=0
(1+cos2x)(1+cos2x-1)=0
(1+cos2x)=0⇒cos2x=-1⇒2x=π+2πn⇒x=π/2+πn⇒x=-π/2∈[-5π/6;π/6]
(1+cos2x-1)=0⇒cos2x=0⇒2x=π/2+πn⇒x=π/4+πn/2⇒x=-3π/4;-π/4∈[-5π/6;π/6]
(2x-3)*4x=6x² (умножение накрест лежащих)
![x-3x=-2x.](https://tex.z-dn.net/?f=x-3x%3D-2x.)
........................................