14. x-6 = x-6
7x+3 5x-1
ОДЗ: 7x+3≠0 5x-1≠0
x≠ -3/7 x≠1/5
(x-6)(5x-1)=(x-6)(7x+3)
(x-6)(5x-1)-(x-6)(7x+3)=0
(x-6)(5x-1-7x-3)=0
(x-6)(-2x-4)=0
x-6=0 -2x-4=0
x=6 -2x= 4
x=-2
Ответ: -2; 6
15. α∈(3π/2; 2π) - 4-ая четверть
cosα - "+"
cosα=√(1-sin²α)=√(1-(2√2/3)²)=√(1- ⁸/₉) = √(1/9)=1/3
3cosα = 3 * (1/3) = 1
Ответ: 1
16.
5tg(5π-γ) - tg(-γ) = 5tg(2*2π -γ)+tgγ = -5tgγ+tgγ= -4tgγ
-4*7= -28
Ответ: -28
17.
(7x³)² : 7х⁶ =49х⁶ : 7х⁶=7
Ответ: 7
18.
1) cos(-3π-β)=cos(-(3π+β))= cos(2π+(π+β))=cos(π+β)=
= -cosβ
2) sin(-π/2+β)=sin(-(π/2-β))= -sin(π/2-β)= -cosβ
3) cos(β+π)=-cosβ
= -2cosβ - cosβ = -3cosβ = 1
-3cosβ -3cosβ
Ответ: 1