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子集Subset. “A is a subset of B” if each element x in A is also an element of B.真子集Proper Subset. “A is a proper subset of B” if all the elements of A are also elements of B, but in addition there exists at least one element c such that 集合的相等Equality of sets. 包含A set A is said to be a subset of a set B,and we write A≦B.We also say that A is contained in B or that B contains A.The relation≦ is referred to as set inclusion.全集（universal set）The Universal Set. This is a set of all elements currently under consideration, often symbolized by Ω.空集（empty set /void set ）A set contains no elements.集合的交(intersect of set)Intersection of set: “A intersect B” is the set of all elements that are both in A and B.集合的并(union of set)Union of sets: “A union B” is the set of all elements that are in A, or B, or both.集合的补(complement of set)Complement of set: “A complement” or “not A” is the set of all elements not in A.常见数集的表达Sets of numbers:The set of all naturalnumbers is designated by NThe set of all integers(positive, negative, and zero) is designated by ZThe set of all rational numbers is designated by QThe set of real numbers is designated by RThe set of all complex numbersis designated by C.常见图形的表达三角形 triangle 圆circle矩形rectangle 正方形 square直线straight line 圆柱cylinder圆锥taper 多边形 polygon四面体 tetrahedron常见的二次曲线的表达椭圆 locus of all points of the plane whose distances to two fixed points(called the foci) add to the same constant双曲线 a hyperbola is a plane curve which is the locus of a point whose distances from two fixed points have a constant difference抛物线 a parabolais a conic section, the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surfaceCatalog of Functions常见函数表达The set A is called thedomain（定义域）of the function f, the set B the codomain（对应域）, and the subset of B consisting of those elements that are images under the function f of some element of its domain is called the range（值域）of the function f. If f associates a in