Х^2+х-2=0
по т. Виета
х1+х2=-1
х1×х2=-2
х1=1
х2=-2
Sin4x-sin(π/2-6x)=2*sin(4x-(π/2-6x))/2
*cos(4x+π/2-6x)/2=
2*sin(4x-π/2+6x)/2*cos((π/2-2x)/2=
2*sin(10x/2-π/2:2)*cos(π/2:2-2x:2)=
2*sin(5x-π/4)*cos(π/4-x)
Х^2-4х+3=0
(х^2-4х+3)'=0 чтобы узнать экстремум
5) - 3(2m + n) + (7m - n) = - 6m - 3n + 7m - n = m - 4n
6) 4x - (5x - (1 - x)) = 4x - (5x - 1 + x) = 4x - 6x + 1 = 1 - 2x
7) a - (b - c) = a - b + c