f(g(x)) means to substitute the right side of g(x) for x in the right side of f(x). So we take the right side of f(x) which is |x| and substitute the right side of g(x), which is (5x+1) for x in |x| getting |5x+1|. so f(g(x)) = |5x+1| ------------------------------------ g(f(x)) means to substitute the right side of f(x) for x in the right side of g(x). So we take the right side of g(x) which is 5x+1 and substitute the right side of f(x), which is |x| for x in 5x+1 getting 5|x|+1. so g(f(x)) = 5|x|+1 Edwin