<span>5х-2(х-3)=6х
</span>5х-2х+6=6х
5x-2x-6x = -6
- 3x = -6
x = -6:-3
x = 2
<span>6х-(2х-5)=2(3х-6)
</span>6x-2x+5 = 6x-12
6x-2x-6x = -12 -5
-2x = -17
x = -17:-2
x = 8.5
Заменой t=tgx сводишь к квадратному
3t^2+t=0
(3t+1)*t=0
t1=-1/3 tgx=-1/3 x=-arctg1/3+пи*k
t2=0 tgx=0 x=пи*k
Х²=75/3
х²=25
х=+-5
Ответ :-5;5