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




                  r                            (x , y1)   r
     (x , y2)         r        y1 = y2
T.KAINOY




     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 = y 2

                                        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

         g    ( x, y )       R Ry            x2                                                y    x2

g ( x)   x2

                                      f(x)                                f       x

                 4            f                                          f ( x) 2 x 2 1

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

                               f (0) 2(0) 2 1                        1

                                f (2)        2(2) 2 1            7

                                f ( 1)       2( 1) 2 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                             Df2 =   { 1,2,3 }   A

                                  f2


                             f2                              Df2   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 =

             x2                                                                         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 1 x n 1 ... a2 x 2 a1 x a0
               an , an 1 ,...,a2 , a1 , a0             n


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

  • 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 r (x , y1) r (x , y2) r y1 = y2
  • 3.
    T.KAINOY 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 = y 2 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 g ( x, y ) R Ry x2 y x2 g ( x) x2 f(x) f x 4 f f ( x) 2 x 2 1 f(0) , f(2) f(-1) f ( x) 2 x 2 1 f (0) 2(0) 2 1 1 f (2) 2(2) 2 1 7 f ( 1) 2( 1) 2 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 Df2 = { 1,2,3 } A f2 f2 Df2 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 = x2 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 1 x n 1 ... a2 x 2 a1 x a0 an , an 1 ,...,a2 , a1 , a0 n f(x) = 2x5+ 3x3 + 4x + 7 5. (Rational Function) f(x) = p(x), q(x) q(x) 0 f(x) = 3 x 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