作业帮数分问题求证明Exercise 8.Suppose on a recent exam,Amy received an A,Joe received a D,Megreceived a B,and Sam received an A.Let R = { Amy,Joe,Meg,Sam }10 1.PREPARATORY MATERIALLet S = {A,B,C,D,F}Let T = {A,B,D}Let f = {(Amy,A),(Joe,D),(Meg,B),(
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数分问题求证明Exercise 8.Suppose on a recent exam,Amy received an A,Joe received a D,Megreceived a B,and Sam received an A.Let R = { Amy,Joe,Meg,Sam }10 1.PREPARATORY MATERIALLet S = {A,B,C,D,F}Let T = {A,B,D}Let f = {(Amy,A),(Joe,D),(Meg,B),(
数分问题求证明
Exercise 8.Suppose on a recent exam,Amy received an A,Joe received a D,Meg
received a B,and Sam received an A.
Let R = { Amy,Joe,Meg,Sam }10 1.PREPARATORY MATERIAL
Let S = {A,B,C,D,F}
Let T = {A,B,D}
Let f = {(Amy,A),(Joe,D),(Meg,B),(Sam,A)}
Let g = {(A,Amy),(D,Joe),(B,Meg),(A,Sam) }
Let h = {(A,Amy),(D,Joe),(B,Meg) }
Use the definition of a function to explain why the following statements are true:
• f is a function from R to T.
• f is not a function from T to R.
• f is a function from R to S.
• g is not a function from T to R.
• h is a function from T to R.
• h is not a function from S to R.
数分问题求证明Exercise 8.Suppose on a recent exam,Amy received an A,Joe received a D,Megreceived a B,and Sam received an A.Let R = { Amy,Joe,Meg,Sam }10 1.PREPARATORY MATERIALLet S = {A,B,C,D,F}Let T = {A,B,D}Let f = {(Amy,A),(Joe,D),(Meg,B),(
其实这道题主要是考查函数的定义：
设A,B是非空的数集,如果按照某种确定的对应关系f,使对于集合A中的任意一个数x,在集合B中都有唯一确定的数f(x)和它对应,那么就称fA→B为从集合A到集合B的一个函数,记作y=f(x),x∈A.
由上定义看出：
定义域内的所有元素都需要用上；
每个元素经过f的作用之后都只能得到唯一一个确定的元素；
值域可以存在元素使得没有定义域内的元素与之对应.
下面看：
• f is a function from R to T.（明显符合上面的定义）
• f is not a function from T to R.（因为同样的一个A对应了Amy和Sam）
• f is a function from R to S.（明显符合上面的定义）
• g is not a function from T to R.（因为同样的一个A对应了Amy和Sam）
• h is a function from T to R.（明显符合上面的定义）
• h is not a function from S to R.（因为定义域S内有元素没有被对应）
有不懂欢迎追问