摘要：This research aimed to describe the students‘ reason in solving the problem of limit function and comparation between high-ability subject (HS) and medium-ability subject (MS). The instrument in this research was the researcher himself as the main instrument guided by the task limit function and valid interview guidelines. Data collection was done by taskbased interviews. The subjects of the study were V-semester students consisting of 2 students (1 subject is having high ability and 1 subject is having medium ability). The research process followed the steps of: (a) formulating the mathematical reasoning indicator in solving the problem of limit function based on theory, (b) formulating the supporting instrument (task limit function and interviewing guide), (c) taking the research subject, (d) taking the data to tell the students‘ reasoning in solving the limit function tests (f) conducting analysis of mathematical reasoning data of the students in solving the problem of function limit, (g) conducting discussion of analysis result, (h) concluding the research results. The result of the research showed that 1) the reasoning equation of the high-ability subject (HS) and the medium ability subject (MS) in solving the function limit problem was to do inductive reasoning first then perform deductive reasoning, 2) difference of reasoning subject with high ability (HS) medium ability (MS) in solving the problem of function limit was only in terms of mathematical reasoning process.
其他摘要：This research aimed to describe the students‘ reason in solving the problem of limit function and comparation between high-ability subject (HS) and medium-ability subject (MS). The instrument in this research was the researcher himself as the main instrument guided by the task limit function and valid interview guidelines. Data collection was done by taskbased interviews. The subjects of the study were V-semester students consisting of 2 students (1 subject is having high ability and 1 subject is having medium ability). The research process followed the steps of: (a) formulating the mathematical reasoning indicator in solving the problem of limit function based on theory, (b) formulating the supporting instrument (task limit function and interviewing guide), (c) taking the research subject, (d) taking the data to tell the students‘ reasoning in solving the limit function tests (f) conducting analysis of mathematical reasoning data of the students in solving the problem of function limit, (g) conducting discussion of analysis result, (h) concluding the research results. The result of the research showed that 1) the reasoning equation of the high-ability subject (HS) and the medium ability subject (MS) in solving the function limit problem was to do inductive reasoning first then perform deductive reasoning, 2) difference of reasoning subject with high ability (HS) medium ability (MS) in solving the problem of function limit was only in terms of mathematical reasoning process.
关键词：mathematical reasoning; high ability subject; medium ability
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