If fog = gof then which of the following is /are false

If f(x)=ax+b and g(x)=cx+d are such that (fog)(x)=(gof)(x) , then which one of the following is correct ?

Find the composition fog and gof and test whether fog = gof when f and g are functions or R given by f(x) =cos x,g(x) = sin x^2

Find the composition fog and gof and test whether fog = gof when f and g are functions or R given by f(x) = g(x)=(1-x^3)^(1/3)

Find the composition fog and gof and test whether fog = gof when f and g are functions or R given by f(x)=x^3 +1, g(x) =x^2 -2

Find the composition fog and gof and test whether fog = gof when f and g are functions or R given by f(x) = sin x, g(x), g(x) =x^5

If the function f:RrarrR be given by f(x)=x^(2)+2 and g:RrarrR be given by g(x)=(x)/(x-1),xne1 , find fog and gof and hence find fog (2) and gof (-3).

If f(x)=3x-2, g(x)=2x+k and if fog=gof, then find the value of k.

Fog is a colloid of solid in gas. True/False?

If f,g:R->R be two functions defined as f(x)=|x|+x and g(x)=|x|-x . Find fog and gof . Hence find fog(-3) , fog(5) and gof(-2) .