Question

cos2x-cos6x=0 на отрезке [-П/2;П]

Answer 1

2cos2x-6cos6x=0

 2cos4x*cos(-2x)=2sin4x*sin2x=0
   x=+Пn/2    [-П/2;0;П/2;П]
    x=Пк/2     [-П/4;П/4;3П/4]

       

Answer 2

2sin4xsin2x=0

sin2x=0  x=Пk/2  [-П/2;0;П/2;П]

sin4x=0 x=Пk/4 [-П/4;П/4;3П/4]