T.KAINOY
                                (function)



                     x1,y1) ∈ r       x1,y2) ∈
          r      y1= y2




1.




     1
           r1 = {(0, 1),(1, 2),(1, 3),(2, 4)}




                            1             2     3
     r2 = {(0, 1),(1, 2),(3, 1),(2, 4)}
T.KAINOY




                                           (


      )
2.

     r = {(x,y) ∈ A× B | P(x,y) }                                x

          P(x,y)               y       x           y         1



     r3 = {(x, y) | y2 = x }                            x=4
          y=2       -2
     r4 = {(x, y) | y = x2 }                             x
            y
     r5= {(x, y) | y = x }                             x=2

     y = 2, -2

3.

                                   y

                                               1
T.KAINOY



               r                                               (x , y1)       r
    (x , y2)       r         y1 = y2
     2                        r = {(x,y)              R    R y2 = 4x +1

}

           y2 = 4x + 1

           (x , y1)      r               y12 = 4a + 1                ….. (1)

           (x , y2)         r                     y22= 4a + 1                     ….. (2)

           (1)          (2)                       y12 = y22

                                    y1 =    y2

                                            y1 = y2


     3                                  r = {(x,y)         R   R y=       x   1   }


                       y=       x   1


          (x , y1)      r                  y1 =    a   1       …..(1)

          (x , y2)       r               y2 =     a    1       …..(2)

           (1)          (2)                       y1 = y2
T.KAINOY



                            y = f(x)                                             y = g(x)


         f       ( x, y )    R       R y             2x              5                                                                        y       2x           5


f ( x)   2x      5
                                                         2                                                                                                     2
         g       ( x, y )   R        R y             x                                                                                            y        x

             2
g ( x)   x

                                            f(x)                                                          f              x

                     4                  f                                                                     f ( x)         2x
                                                                                                                                  2
                                                                                                                                          1


                                        f(0) , f(2)                                              f(-1)
                                                             2
                                    f ( x)           2x              1
                                                                             2
                                             f (0)               2(0)                1           1

                                                                 2
                                    f (2)            2(2)                    1               7
                                                                         2
                                    f ( 1)            2 ( 1)                     1           1

                     5                                               f (1)            2                   f (x         1)        1
                                                                                                                                              2
                                                                                                                                                                       x
                                                                                                                                          f (x)



                                                     f (4)

                                                                             2
                                 f (x           1)       1                                           f (1)       2
                                                                     f (x)
                                                                                                      2                  2
                                x       1                                        f (2)       1                   1                2
                                                                                                     f (1)               2
                                                                                                          2                  2
                                 x          2                                        f (3)       1                   1                2
                                                                                                      f (2)                  2
                                                                                                          2                  2
                                 x      3                                            f (4)       1                   1                2
                                                                                                      f (3)                  2




         1.                                      A                   B                    (f : A               B)
T.KAINOY



                      Df = A              Rf        B

     6           A = {1,2,3,4}                   B = {3,6,7,8}

     1.       f1 = { (1,3) , (2,6) , (3,7) , (4,8) }
                           f1                            D f1   = { 1,2,3,4, } = A

          f1                              A        B

     2.       f2 = { (1,6) , (2,7) , (3,8) }
                      f2                             D f2   = { 1,2,3 }    A

                                 f2


                            f2                              D f2    B

2.               A                    B (f : A    onto
                                                            B)


                      Df = A             Rf = B




3.                1 – 1 (One – to – one function )

          f                                        1-1




                  2
T.KAINOY




          f

     A                 B         A              B
              f1
     1                 x                   f2
                                 m
                                                 x
     2                 y
                                 o
                                                 y
     3                 z
                                 n




              f1           1-1

         f2                          1-1

                                            many-to-one




                   f       1–1



1.
                                                           X
                                                           X
                             1
                                                1–1
2.                                                    X
T.KAINOY



                                                                                             1-1
                                                                                        many – to – one
        3.
                     (x1,y)        f                 (x2,y)                 f

                                                             x1 = x 2

                                                                                                     1-1

                 7                          f                                                  f ={(x , y)     R   R

X   1   +    Y   1   =2}

                                                 f                                            1-1

                       (x1,y)          f                     (x2,y)                 f

                                           x1        1       +        y    1        =2               ….. (1)

                              x2   1   +             y       1    =2                          …...(2)

             (1)=(2)                        x1           1   =        x2        1


                                                 x1      +1=               x2       +1

                                                                 x1   =    x2


                                                                                               1-1

                 8                          f = {(x , y)                            R        R y = x 2}

                                       f                     1-1

                       (x1,y)          f                     (x2,y)                 f

                           y = x 12                                       …….. (1)

                           c = x 22                                       …….. (2)

                           x12= x22                                   x1 =              x2
T.KAINOY



                                              x1 = x2

                 f                                 1-1

                                                                            y
             x                                                                       y




    4.                               A        B”       (f:A     1 1
                                                                       B)
                         Df = A          Rf            B       “            y

                     x                             ”

    5.                               A                 B (f:A               B)
                         Df = A          Rf = B            “           y

         x                   ”




f                        A       B                                 f

                     4
T.KAINOY




1.           (Constant Function)
     f (x) = a           (           )
       f (x) = 2 , f (x) = -3
2.               (Linear Function)
     f (x) = ax + b             (        )
T.KAINOY



         f (x) = 5x+3 , f (x) = 4x
3.                                 (Quadratic Function)
       f (x) = ax2+ bx + c                                    (                          )
                f (x) = 3x2+ 2x + 1 , f (x) = 7x2- 4
4.                          (Polynomial Function)
      f(x) =    an x
                       n
                               an 1x
                                       n 1
                                             ...   a2 x
                                                          2
                                                              a1 x   a0

               a n , a n 1 ,..., a 2 , a 1 , a 0                          n



              f(x) = 2x5+ 3x3 + 4x + 7
5.                             (Rational Function)
     f(x) =                             p(x), q(x)                                q(x)       0
          f(x) =           3x
                               2
                                   2
                           x       1




6.                                 (Absolute Value Function)

     f (x) = ax + b + c                               (                       )

              f(x)             x




7.                                 step function)
T.KAINOY




8.           periodic function)
         f                        p        f(x+p)
= f(x)          x     x+p             f

ฟังก์ชัน(function)

  • 1.
    T.KAINOY (function) x1,y1) ∈ r x1,y2) ∈ r y1= y2 1. 1 r1 = {(0, 1),(1, 2),(1, 3),(2, 4)} 1 2 3 r2 = {(0, 1),(1, 2),(3, 1),(2, 4)}
  • 2.
    T.KAINOY ( ) 2. r = {(x,y) ∈ A× B | P(x,y) } x P(x,y) y x y 1 r3 = {(x, y) | y2 = x } x=4 y=2 -2 r4 = {(x, y) | y = x2 } x y r5= {(x, y) | y = x } x=2 y = 2, -2 3. y 1
  • 3.
    T.KAINOY r (x , y1) r (x , y2) r y1 = y2 2 r = {(x,y) R R y2 = 4x +1 } y2 = 4x + 1 (x , y1) r y12 = 4a + 1 ….. (1) (x , y2) r y22= 4a + 1 ….. (2) (1) (2) y12 = y22 y1 = y2 y1 = y2 3 r = {(x,y) R R y= x 1 } y= x 1 (x , y1) r y1 = a 1 …..(1) (x , y2) r y2 = a 1 …..(2) (1) (2) y1 = y2
  • 4.
    T.KAINOY y = f(x) y = g(x) f ( x, y ) R R y 2x 5 y 2x 5 f ( x) 2x 5 2 2 g ( x, y ) R R y x y x 2 g ( x) x f(x) f x 4 f f ( x) 2x 2 1 f(0) , f(2) f(-1) 2 f ( x) 2x 1 2 f (0) 2(0) 1 1 2 f (2) 2(2) 1 7 2 f ( 1) 2 ( 1) 1 1 5 f (1) 2 f (x 1) 1 2 x f (x) f (4) 2 f (x 1) 1 f (1) 2 f (x) 2 2 x 1 f (2) 1 1 2 f (1) 2 2 2 x 2 f (3) 1 1 2 f (2) 2 2 2 x 3 f (4) 1 1 2 f (3) 2 1. A B (f : A B)
  • 5.
    T.KAINOY Df = A Rf B 6 A = {1,2,3,4} B = {3,6,7,8} 1. f1 = { (1,3) , (2,6) , (3,7) , (4,8) } f1 D f1 = { 1,2,3,4, } = A f1 A B 2. f2 = { (1,6) , (2,7) , (3,8) } f2 D f2 = { 1,2,3 } A f2 f2 D f2 B 2. A B (f : A onto B) Df = A Rf = B 3. 1 – 1 (One – to – one function ) f 1-1 2
  • 6.
    T.KAINOY f A B A B f1 1 x f2 m x 2 y o y 3 z n f1 1-1 f2 1-1 many-to-one f 1–1 1. X X 1 1–1 2. X
  • 7.
    T.KAINOY 1-1 many – to – one 3. (x1,y) f (x2,y) f x1 = x 2 1-1 7 f f ={(x , y) R R X 1 + Y 1 =2} f 1-1 (x1,y) f (x2,y) f x1 1 + y 1 =2 ….. (1) x2 1 + y 1 =2 …...(2) (1)=(2) x1 1 = x2 1 x1 +1= x2 +1 x1 = x2 1-1 8 f = {(x , y) R R y = x 2} f 1-1 (x1,y) f (x2,y) f y = x 12 …….. (1) c = x 22 …….. (2) x12= x22 x1 = x2
  • 8.
    T.KAINOY x1 = x2 f 1-1 y x y 4. A B” (f:A 1 1 B) Df = A Rf B “ y x ” 5. A B (f:A B) Df = A Rf = B “ y x ” f A B f 4
  • 9.
    T.KAINOY 1. (Constant Function) f (x) = a ( ) f (x) = 2 , f (x) = -3 2. (Linear Function) f (x) = ax + b ( )
  • 10.
    T.KAINOY f (x) = 5x+3 , f (x) = 4x 3. (Quadratic Function) f (x) = ax2+ bx + c ( ) f (x) = 3x2+ 2x + 1 , f (x) = 7x2- 4 4. (Polynomial Function) f(x) = an x n an 1x n 1 ... a2 x 2 a1 x a0 a n , a n 1 ,..., a 2 , a 1 , a 0 n f(x) = 2x5+ 3x3 + 4x + 7 5. (Rational Function) f(x) = p(x), q(x) q(x) 0 f(x) = 3x 2 2 x 1 6. (Absolute Value Function) f (x) = ax + b + c ( ) f(x) x 7. step function)
  • 11.
    T.KAINOY 8. periodic function) f p f(x+p) = f(x) x x+p f