Question

А) 2cos^2 5x+cos3x=1 б) sin5x + sinx +2 cos^2x=1

Answer 1

1
2cos²5x-1+cos3x=0
cos10x+cos3x=0
2cos13x/28xos7x/2=0
cos13x/2=0⇒13x/2=π/2+πn⇒x=π/13+2πn/13,n∈z
cos7x/2=0⇒7x/2=π/2+πk⇒x=π/7+2πk/17,k∈z