Step-by-step explanation:
f(g(x))= f(2x)
f(g(x))=3+cos2x
g(f(x))=g(3+cosx)
g(f(x))=2(3+cosx)
g(f(x))=6+2cosx
where,
f(g(x))=g(f(x))
3+cos2x=6+2cosx
2cosx-cos2x+6-3=0
2cosx-cos2x+3=0
x=2pi n1+pi
n1€ z
