2) 5x - x^2 = 0 или Ctg(x + 
) = 0
x = 0 или x = 5, или Ctg= -
x = 5π/6 + πk, k Є Z
3) a) 2Cos3x + Sin3x = 0
3Sin3x = 0
Sin3x = 0
3x = πk, k Є Z
x = πk/3, k Є Z
б) 6Sin^2x + SinxCosx - Cos^2x = 2*1
6Sin^2^2x + SinxCosx - Cos^2x = 2*(Sin^2x + Cos^2x)
6Sin^2x + SinxCosx - Cos^2x - 2 Sin^2x - 2Cos^2x= 0
4Sin^2x +SinxCosx - 3Cos^2x = 0 | : Cos^2x
4tg^2x + tgx -3 = 0
решаем как квадратное: D = 25
a) tgx = 1/2 б) tgx = -3/4
x = -arctgx(1/2) + πk, k Є Z х = -arctg(3/4) + πk, k Є Z