This is the Solution of Question From RD SHARMA book of CLASS 11 CHAPTER LIMITS AND DERIVATIVES This Question is also available in R S AGGARWAL book of CLASS As an example, a classic result of Ritt shows that permutable polynomials are, up to a linear homeomorphism, either both powers of x, both iterates of the same polynomial, or both Chebychev polynomials We say f and g commute (with respect to composition) The property is called "commutativity"Learn how to solve f(g(x)) by replacing the x found in the outside function f(x) by g(x) Consider Two Function F X Lim N Oo Cosx Sqrt N N And G F x ax g x x 2-4x 9