Решение удалишь...............................................
3(x-y)-6=x+y
2(x-y)-9=x+y
3x-3y-6-x-y=0
2x-2y-9-x-y=0
2x-4y-6=0
x-3y-9=0
x=3y-9
2(3y+9)-4y-6=0
6y+18-4y-6=0
2y=-12
y=-6
x=3×(-6)+8
x=-9
Ответ:x=-9;y=-6
6tg^2x + tgx - 1 = 0
Замена: tgx = t
6t^2 + t - 1 =0
D = 1 + 24 = 25
t1/2 =-0,75 ; -0.5
tgx = -0,5
x = -arctg0,5 + pi K
x = -arctg0,75 + pi K