How do you find the compositions given #f(x) = x/(x + 1)#, #g(x) = x^2 - 1#? Precalculus Functions Defined and Notation Function Composition 1 Answer Konstantinos Michailidis Jan 25, 2016 For f(x) the domain is #R-{1}# and for g(x) is #R# where #R# is the set of real numbers. Hence #f(g(x))=(x^2-1)/(x^2-1+1)=(x^2-1)/(x^2)=1-1/(x^2)# and #g(f(x))=(x/(x+1))^2-1# Answer link Related questions What is function composition? What are some examples of function composition? What are some common mistakes students make with function composition? Is function composition associative? Is it always true that #(f@g)(x) = (g@f)(x)#? If #f(x) = x + 3# and #g(x) = 2x - 7#, what is #(f@g)(x)#? If #f(x) = x^2# and #g(x) = x + 2#, what is #(f@g)(x)#? If #f(x) = x^2# and #g(x) = x + 2#, what is #(g@f)(x)#? What is the domain of #(f@g)(x)#? What is the domain of the composite function #(g@f)(x)#? See all questions in Function Composition Impact of this question 935 views around the world You can reuse this answer Creative Commons License