Cos(2*7x) + sin(7x) = 1
1 - 2sin^2(7x) + sin(7x) = 1
sin(7x)*(1 - 2sin(7x)) = 0
1) sin(7x) = 0
7x = πk
x = πk/7
2) sin(7x) = 1/2
7x = π/6 + 2πk, x = π/42 + 2πk/7
7x = 5π/6 + 2πk, x = 5π/42 + 2πk/7
X^2-5x-6>=0
D=25+24=49=7^2
x1=-1 ; x2=6
Ответ: (-бесконечности; -1] U [6; +бесконечности)
Решение находится во вложении