3tg^2(x/3)-2tgx/3-1=0
tgx/3=t
3t^2-2t-1=0
t=1/3(1+-2)
t1=-1/3
t2=1
tgx/3=1 x=3П/4+3пk
tgx=-1/3 x=3arctg(-1/3)+3Пk
-.-.-.-.-.-.-.-.-.-.-.-.-.
Lg (2x² - 4x + 12) = lg(x*(x+3))
2x² - 4x +12 = x² +3x
x²- 7x +12 =0
D = 49-48 = 1
x₁ = (7+1) /2 =4
x₂ = (7-1) /2=3
Ответ: 4; 3
-3x-1 >= -6x
-3x + 6x >= 1
3x >= 1
x >= 1/3