ABSTRACT
The purpose of this article is to explain how a Realistic Mathematics Education (RME) approach can develop student understanding of the composition and decomposition of a function. The background of this article is based on difficulties experienced by students when they were decomposing a function, especially when they had to find f(x) if f∘g(x) and g(x) were given. This article uses design research methodology and was implemented for senior high school students in Jakarta, Indonesia. Retrospective analysis showed that the learning trajectory, which was developed at preliminary design, could help students to understand the composition and decomposition of a function concept. As a result, students developed the inverse of g(x) as a strategy for decomposing function fog(x). Therefore, it could be a recommendation for teachers to introduce inverse learning before students learn about function decomposition.
