1)Пусть tgx=n
27ⁿ+81*27⁻ⁿ-30=0
27ⁿ+81/27ⁿ-30=0
27²ⁿ-30*27ⁿ+81=0
2)Пусть 27ⁿ =b
b²-30b+81=0
D=576
b₁=27⇒27ⁿ=27⇒n=1
b₂=3⇒3³ⁿ=3⇒n=1/3
3)a)tg²x=1⇒tgx=1⇒x=π/4+πn
tgx=-1⇒x=-π/4+πn
b)tg²x=1/3
tgx=√3/3⇒x=π/6+πn
tgx=-√3/3⇒x=-π/6+πn
4)[3π/2;3π]
x=9π/4; 7π/4;11π/4; 11π/6; 13π/6; 16π/6.