Pls explain why fog and gof are not equal?......................

Dear student
                       Two functions are not equal in this case because the domain of f(x) and g(x) are not equal.
                        As you can see domain of f(x) is all real numbers.
                       But domain of g(x) is x > 0.
                         so domain of f(g(x)) is x>0  
                         and  domain of g(f(x)) is all real numbers
                        Therfore f(g(x)) is not equal to g(f(x))​​​​​​​​
Regards