Analisis Kesalahan Peserta Didik dalam Menyelesaikan Soal Esai Matematika pada Materi Fungsi Komposisi dan Fungsi Invers

This research aims to analyze students' errors in solving mathematical description questions on compositional functions and inverse functions at SMA Negeri 1 Perbaungan. This research used a descriptive qualitative method with the subjects being class XI students who were selected using purposive sampling. Data was collected through description tests and interviews, then analyzed using data reduction techniques, data presentation and drawing conclusions. In addition, the level of students' abilities and the percentage of types of errors are also analyzed. The research results show that students experience various errors, including conceptual errors, procedural errors and computational errors. Conceptual errors occur because students do not understand the definition and nature of function, while procedural errors arise due to errors in problem solving steps. Meanwhile, calculation errors are caused by carelessness in algebraic operations. Percentage analysis shows that conceptual errors 41.21% are the most dominant type of error, followed by procedural errors 26.06% and calculation errors 18.79%. The results of this research can be used as evaluation material for teachers in designing more effective learning strategies to reduce students' errors in understanding and solving mathematics problems.