Tài liệu tham khảo Tài liệu trung cấp môn Kinh tế vi mô bằng tiếng Anh gồm 41 phần giúp sinh viên khoa kinh tế học tốt môn Kinh tế vi mô. Tài liệu này là phần 39 giới thiệu về " Tóan học phụ lục - Mathematical Appendix " | MMHEMATICAL APPENDIX In this Appendixwe will provide a brief review of some of the mathematical concepts that areused in the text. This material is meant to serve as a reminder of the definitions of various terms used in the text. It is emphatically not a tutorial in mathematics. The definitions given will generally be the simplest not the most rigorous. Functions A function is a nilethat describes a relationship between numbers. For each number X a function assigns a unique number y according to some rule. Thus a function can be indicated by describing the rule as take a number and squme it or take a number and multiply it by 2 and so on. We write these particular functions as y X2 y 2an Functions are sometimes referred to as transformations. Often we want to indicate that some variable y depends on some other variable X but we don t know the specific algebraic relationship between the two variables. In this case we write y f x which should be interpreted as saying that the variable y depends on X according to the rule f. Given a function y - the number X is often called the independent variable and the number y is often called the dependent variable. A2 MATHEMATICAL APPENDIX The idea is that x varies independently but the value of y depends on the value of x. C Often some variable y depends on several other variables rr x 2. and so on so we write y 2 to indicate that both variables together determine the value of y. Graphs A graph of a function depicts the behavior of a function pictorially. Figure AT shows two graphs of functions. In mathematics the independent variable is usually depicted on the horizontal axis and the dependent variable is depicted on the vertical axis. The graph then indicates the relationship between the independent and thé dependent variables. However in economics it is common to graph functions with the independent variable on the vertical axis and the dependent variable on the horizontal axis. Demand functions for example are .
