STEPENOVANJE


Proizvod a ⋅ a ⋅ ... ⋅ a = a n naziva se n -tim stepenom broja. Ako je a ∈ R , a ≠ 0 i neka je n ∈ N
                n − puta



Po definiciji je:

                                                                      0
                                               ⎛4⎞
      1) a 0 = 1 → primer: 50 = 1, (−3) 0 = 1, ⎜ ⎟ = 1
                                               ⎝7⎠
                 1                  1 1            1   1
      2) a − n = n → primer: 3− 2 = 2 = , 5−3 = 3 =
                a                   3     9        5 125
______________________________________________________________________

Još važe sledeća pravila:

         3)   a m ⋅ a n = a m+n       →   primer:   32 ⋅ 35 = 32+5 = 37
         4)   a m : a n = a m−n       →   primer:   710 : 7 6 = 710−6 = 7 4
         5)   ( a m ) n = a m⋅ n      →   primer:   (23 ) 5 = 23⋅5 = 215
         6)   ( a ⋅ b) = a n ⋅ b n    →   primer:   (12 ⋅11) 5 = 125 ⋅112
                    n                                   2
            ⎛a⎞  an                            ⎛7⎞  72
         7) ⎜ ⎟ = n                   → primer ⎜ ⎟ = 2
            ⎝b⎠  b                             ⎝4⎠  4
                    −n            n                     −2        2
            ⎛a⎞             ⎛b⎞                ⎛2⎞   ⎛3⎞  32 9
         8) ⎜ ⎟            =⎜ ⎟       → primer ⎜ ⎟ = ⎜ ⎟ = 2 =
            ⎝b⎠             ⎝a⎠                ⎝3⎠   ⎝2⎠  2    4

O čemu treba voditi računa?

Treba paziti na zapis: (−5) 2 = (−5)(−5) = 25 , dok − 52 = −5 ⋅ 5 = −25 . Uopšteno važi:

(− a) paran = a paran
(− a) neparan = − a neparan

Dakle, paran izložilac ‘’uništi’’ minus.




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                                                                                                 1
ZADACI


                 ( 27 : 25 ) ⋅ 23
1) Izračunati:
                     24 : 22

      (27 : 25 ) ⋅ 23 27 −5 ⋅ 23 22 ⋅ 23 22+3 25
                     =          =       = 2 = 2 = 25 − 2 = 23 = 8
         24 : 22        24 − 2     22     2   2
_____________________________________________________________



                 35 ⋅ 93
2) Izračunati:
                 27 2 ⋅ 3

35 ⋅ 93 35 ⋅ (32 )3 35 ⋅ 36 35
       = 3 2 1 = 6 1 = 1 = 35−1 = 34 = 3 ⋅ 3 ⋅ 3 ⋅ 3 = 81
27 ⋅ 3 (3 ) ⋅ 3
   2
                    3 ⋅3 3


______________________________________________________________


                 ( x 4 )3 ⋅ x 3 : x 5
3) Izračunati:                        =
                    ( x 5 : x 2 )3

      ( x 4 ) 3 ⋅ x 3 : x 5 x12 ⋅ x 3 : x 5 x12+ 3−5 x10
                           =               = 3 3 = 9 = x10−9 = x1 = x
         ( x 5 : x 2 )3       ( x 5− 2 ) 3  (x )     x
_______________________________________________________________


                 3n +1 ⋅ 3n + 2
4) Izračunati:
                   32 n + 4

      3 n +1 ⋅ 3 n + 2 3 n +1+ n + 2 3 2 n + 3
                          = 2 n + 4 = 2 n + 4 = Pazi pa zagrade zbog minusa
          32n+ 4                 3              3
                                                            1 1
      = 3( 2 n + 3) −( 2 n + 4 ) = 32 n +3− 2 n − 4 = 3−1 = 1 =
                                                           3 3
_______________________________________________________________



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                                                                                        2
5)   Izračunati 0,5−1 + 0,25−2 + 0,125−3 + 0,0625−4
        0,5−1 + 0,25−2 + 0,125−3 + 0,0625−4 =
                −1               −2            −3               −4
         ⎛1⎞  ⎛1⎞  ⎛1⎞  ⎛1⎞
         ⎜ ⎟ +⎜ ⎟ +⎜ ⎟ +⎜ ⎟ =
         ⎝2⎠  ⎝4⎠  ⎝8⎠  ⎝ 16 ⎠
                1            2             3                4
      ⎛ 2 ⎞ ⎛ 4 ⎞ ⎛ 8 ⎞ ⎛ 16 ⎞
      ⎜ ⎟ +⎜ ⎟ +⎜ ⎟ +⎜ ⎟ =
      ⎝1⎠ ⎝ 2⎠ ⎝1⎠ ⎝ 1 ⎠
      21 + 4 2 + 83 + 16 4 = 2 + 16 + 512 + 65536 = 66066
_________________________________________________________________


6) Izračunati 1−1 + 2 −2 + 3−3 + (−1) −1 + (−2) −2 + (−3) −3
      1−1 + 2 −2 + 3−3 + (−1) −1 + (−2) −2 + (−3) −3 =
       1 1 1             1        1         1
        + 2+ 3+              +         +        =
       1 2 3 (−1) (−2) (−3) 3
                           1         2


          1 1            1 1 1 1 2 1
      1+ +         −1+ −          = + = =
          4 27           4 27 4 4 4 2
_________________________________________________________________


                                          −4            2            −2
                             ⎛1⎞ ⎛3⎞              ⎛5⎞
7) Ako je            a = 5 ⋅ ⎜ ⎟ ⋅ ⎜ ⎟ i b = 10 3 ⎜ ⎟
                             3
                                                                          nadji a ⋅ b −1
                             ⎝4⎠ ⎝2⎠              ⎝3⎠



                       −4             2                     4
              ⎛1⎞ ⎛3⎞                  ⎛4⎞ 3
                                                 2
                                                      53 ⋅ 44 ⋅ 32
     a = 53 ⋅ ⎜ ⎟ ⋅ ⎜ ⎟ = 53 ⋅ ⎜ ⎟ ⋅ 2 =
              ⎝4⎠ ⎝2⎠                  ⎝1⎠ 2               22
       53 ⋅ (22 ) 4 ⋅ 32
     =         2
                         = 53 ⋅ (22 )3 ⋅ 32 = 53 ⋅ 26 ⋅ 32
             2
                        −2                          2
                          ⎛ 3 ⎞ 10 ⋅ 3    (5 ⋅ 2)3 ⋅ 32 53 ⋅ 23 ⋅ 32
                                  3   2
              ⎛5⎞
     b = 10 ⋅ ⎜ ⎟ = 103 ⋅ ⎜ ⎟ =
            3
                                        =              =             = 5 ⋅ 23 ⋅ 32
              ⎝ 3⎠        ⎝ 5⎠    52           52            52

Konačno:                    izračunati i a ⋅ b −1

                         1
         a ⋅ b −1 = 53 ⋅ 26 ⋅ 32 ⋅
                              = 52 ⋅ 23 = 25 ⋅ 8 = 200
                     5⋅ 2 ⋅3
                         3  2

______________________________________________________________


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                                                                                                              3
⎛ ⎛ 5 x −5 ⎞ −2 ⎛ y −1 ⎞ −3 ⎞
8) Izračunati ⎜ ⎜ − 2 ⎟ ⋅ ⎜ −1 ⎟ ⎟ : 10 x 2 y −3
              ⎜ ⎜ 2 y ⎟ ⎜ 5x ⎟ ⎟
              ⎝⎝         ⎠ ⎝         ⎠ ⎠
       ⎛ ⎛ 5 x −5 ⎞ −2 ⎛ y −1 ⎞ −3 ⎞
       ⎜⎜                          ⎟
         ⎜ 2 y − 2 ⎟ ⋅ ⎜ 5 x −1 ⎟ ⎟ : 10 x y =
                                          2 −3
       ⎜           ⎟ ⎜          ⎟
       ⎝⎝          ⎠ ⎝          ⎠ ⎠
       ⎛ 5−2 ⋅ x10      y3 ⎞
       ⎜ − 2 4 ⋅ −3 3 ⎟ : 10 x 2 y −3 =
       ⎜                        ⎟
       ⎝ 2 ⋅y 5 ⋅x ⎠
       (5− 2+3 ⋅ x10−3 ⋅ y 3− 4 ⋅ 2 2 ) : 10 x 2 y −3 =
      (51 ⋅ x 7 ⋅ y −1 ⋅ 4) : 10 x 2 y −3 =
      20 7 − 2 −1−( −3)
          x y               = 2 x 5 y −1+ 3 = 2 x 5 y 2
      10
__________________________________________________________

               1 −3 1 − 4
                 10 + 10
9) Ako je 10 =
            x  2       2                                   Odrediti x.
                  55 ⋅10 −7

       1 −3 1 − 4         1       1
         10 + 10              +
       2        2      = 2000 20000 = Izvučemo gore zajednički
          55 ⋅10 −7
                              55
                          10000000
         1 ⎛       1⎞     1 11         11
            ⎜1 + ⎟           ⋅
       2000 ⎝ 10 ⎠ 2000 10
                      =          = 20000 =
            55             55          55
         10000000       10000000 10000000
       11⋅10000000 11⋅10000000 10000000
                     =              =        = 100 = 102
         20000 ⋅ 55     11⋅100000     100000


sada je 10 x = 10 2 , dakle x = 2
________________________________________________________

10)
       a) A ⋅10 −5 = 0,2 ⋅ 0,008                      b)     B ⋅10 −6 = 0,04 ⋅ 0,006
            A ⋅10 −5 = 2 ⋅10 −1 ⋅ 8 ⋅10 −3                   B ⋅10 −6 = 4 ⋅10 − 2 ⋅ 6 ⋅10 −3
            A ⋅10 −5 = 16 ⋅10 − 4                            B ⋅10 −6 = 24 ⋅10 −5
                16 ⋅10 − 4                                       24 ⋅10 −5
            A=                                               B=
                  10 −5                                           10 −6
            A = 16 ⋅10 −4−( −5)                              B = 24 ⋅10 −5+ 6
            A = 16 ⋅10 −4+5                                  B = 24 ⋅10
            A = 16 ⋅10                                       B = 240
            A = 160                                                                            4
Ovde smo koristili zapisivanje realnog broja u sistemu sa osnovnim 10. Ovo je dobra

opcija kada je broj ‘’glomazan’’.


Primeri:

   1) Brzina svetlosti je približno c ≈ 300000000m / s a mi je ‘’lakše’’ zapisujemo
      c ≈ 3 ⋅108 m / s , 108 -znači da ima 8 nula iza jedinice!!!
         1           1      1           2
   2)          =          = ⋅10 −5 = ⋅10 −5 = 2 ⋅10 −1 ⋅10 −5 = 2 ⋅10 −6
      500000 5 ⋅10      5
                            5         10
                           −5        −5
   3) 0,000069 = 6,9 ⋅10 ≈ 7 ⋅10
   4) Površina zemlje je 510083000km 2 ali mi zapisujemo ≈ 5 ⋅108 km 2




               ⎛ 3a − x   2a − x    ax ⎞    a−x
11) Izračunati ⎜        −        − 2x ⎟ : x
               ⎜ 1− a−x 1+ a−x a −1 ⎟ a − a−x
               ⎝                       ⎠

       ⎛ 3a − x    2a − x    ax ⎞        a−x
       ⎜ 1− a−x − 1+ a−x − a2x −1 ⎟ : a x − a−x =
       ⎜                          ⎟
       ⎝                          ⎠
       ⎛ 3          2           ⎞        1
       ⎜ ax          x      ax ⎟          x
       ⎜        − a − 2x ⎟ : a                =
             1
       ⎜ 1− x 1+ x    1 a −1 ⎟ x 1
                                    a − x
       ⎝ a           a          ⎠           a
       ⎛ 3        2           ⎞    1
       ⎜ x         x    ax ⎟ ax
       ⎜ xa − a −             ⎟:         =
       ⎜ a −1 a x + 1 a2 x −1 ⎟ a2 x −1
       ⎜ x                    ⎟
       ⎝ a        ax          ⎠ ax
       ⎛ 3       2          ax        ⎞    1
       ⎜ x    − x    − x              ⎟ : 2x =
       ⎝ a − 1 a + 1 (a − 1)(a + 1) ⎠ a − 1
                                x


        3(a x + 1) − 2(a x − 1) − a x a 2 x − 1
                                     ⋅          =
              (a x − 1)(a x + 1)          1
        3a x + 3 − 2a x + 2 − a x (a − 1)(a + 1)
                                    x      x

                                 ⋅               =
            (a x − 1)(a x + 1)          1
       = 3+ 2 = 5

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                                                                                          5
⎛ x − x −2          x − x −1        ⎞ 1 − x −1
12)   Izračunati      ⎜ x + x −1 + 1 1 + x − 2 + 2 ⋅ x −1 ⎟ : 1 + x −1
                      ⎜ −2          −                     ⎟
                      ⎝                                   ⎠


      ⎛ x − x −2        x − x −1     ⎞ 1 − x −1
      ⎜ −2    −1
                   −    −2        −1 ⎟
                                       :     −1
                                                =
      ⎝ x + x +1 1+ x + 2 ⋅ x ⎠ 1+ x
      ⎛      1          1 ⎞          1
      ⎜ x − x2       x−
                        x    ⎟ 1− x
      ⎜ 1 1      −              :        =
                      1 2⎟
      ⎜ 2 + +1 1+ 2 + ⎟ 1+ 1
      ⎝x    x         x    x⎠        x
      ⎛ x3 − 1        x2 − 1 ⎞         x −1
      ⎜                      ⎟
      ⎜    x2      − 2 x     ⎟:          x =
      ⎜ 1+ x + x
                 2
                    x +1+ 2x ⎟         x +1
      ⎜                      ⎟
      ⎝    x2          x2    ⎠           x
      ⎛ ( x − 1) ( x 2 + x + 1) x( x − 1) ( x + 1)   ⎞ x −1
      ⎜                        −                     ⎟:     =
      ⎜       x2 + x + 1            ( x + 1) 2       ⎟ x +1
      ⎝                                              ⎠

      ⎛ x − 1 x( x − 1) ⎞ x − 1
      ⎜        −            ⎟:        =
      ⎝ 1            x +1 ⎠ x +1
      ( x − 1)( x + 1) − x( x − 1) x + 1
                                    ⋅      =
                   x +1               x −1
       ( x − 1) [ ( x + 1) − x ] x + 1
                                ⋅        = x +1− x = 1
                x +1              x −1



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                                                                                            6
⎛ an          a −n ⎞ ⎛ a n          a −n ⎞
13) Izračunati A = ⎜            +        ⎟−⎜
                     ⎜ 1 − a −n 1 + a −n ⎟ ⎜ 1 + a −n 1 − a −n ⎟
                                                       +       ⎟
                     ⎝                   ⎠ ⎝                   ⎠
          ⎛ a  n
                        a −n
                               ⎞ ⎛ a   n
                                               a −n
                                                      ⎞
       A=⎜       −n
                    +            −
                            −n ⎟ ⎜       −n
                                            +      −n ⎟
          ⎝ 1− a      1+ a ⎠ ⎝ 1+ a           1− a ⎠
            ⎛           1 ⎞ ⎛             1 ⎞
            ⎜ an         n  ⎟ ⎜ an         n  ⎟
        A=⎜         + a ⎟−⎜            + a ⎟
            ⎜ 1 − 1n 1 + 1n ⎟ ⎜ 1 + 1n 1 − 1n ⎟
            ⎝ a          a ⎠ ⎝ a           a ⎠
            ⎛ a  n
                        1 ⎞ ⎛             1 ⎞
            ⎜               ⎟ ⎜ an            ⎟
        A = ⎜ n1 + n
                         n
                       a ⎟−⎜           + nan ⎟
            ⎜ a −1 a +1 ⎟ ⎜ a +1 a −1 ⎟
                                  n

            ⎜ n             ⎟ ⎜ n             ⎟
            ⎝ a        an ⎠ ⎝ a           an ⎠
            ⎛ a 2n     1 ⎞ ⎛ a 2n        1 ⎞
        A=⎜ n       + n    ⎟−⎜ n      + n ⎟
            ⎝ a −1 a +1 ⎠ ⎝ a +1 a −1 ⎠
             a 2 n (a n + 1) + 1(a n − 1) a 2 n (a n − 1) + 1(a n + 1)
        A=                               −
                   (a n − 1)(a n + 1)           (a n + 1)(a n − 1)
             a 3n + a 2 n + a n − 1 − (a 3n − a 2 n + a n + 1)
        A=
                            (a n − 1)(a n + 1)
             a 3n + a 2 n + a n − 1 − a 3n + a 2 n − a n − 1
        A=
                           (a n − 1)(a n + 1)
                 2a 2 n − 2       2(a 2 n − 1)   2(a n − 1)(a n + 1)
        A=                     = n              = n                  =2
             (a n − 1)(a n + 1) (a − 1)(a n + 1) (a − 1)(a n + 1)



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                                                                                             7

Stepenovanje

  • 1.
    STEPENOVANJE Proizvod a ⋅a ⋅ ... ⋅ a = a n naziva se n -tim stepenom broja. Ako je a ∈ R , a ≠ 0 i neka je n ∈ N n − puta Po definiciji je: 0 ⎛4⎞ 1) a 0 = 1 → primer: 50 = 1, (−3) 0 = 1, ⎜ ⎟ = 1 ⎝7⎠ 1 1 1 1 1 2) a − n = n → primer: 3− 2 = 2 = , 5−3 = 3 = a 3 9 5 125 ______________________________________________________________________ Još važe sledeća pravila: 3) a m ⋅ a n = a m+n → primer: 32 ⋅ 35 = 32+5 = 37 4) a m : a n = a m−n → primer: 710 : 7 6 = 710−6 = 7 4 5) ( a m ) n = a m⋅ n → primer: (23 ) 5 = 23⋅5 = 215 6) ( a ⋅ b) = a n ⋅ b n → primer: (12 ⋅11) 5 = 125 ⋅112 n 2 ⎛a⎞ an ⎛7⎞ 72 7) ⎜ ⎟ = n → primer ⎜ ⎟ = 2 ⎝b⎠ b ⎝4⎠ 4 −n n −2 2 ⎛a⎞ ⎛b⎞ ⎛2⎞ ⎛3⎞ 32 9 8) ⎜ ⎟ =⎜ ⎟ → primer ⎜ ⎟ = ⎜ ⎟ = 2 = ⎝b⎠ ⎝a⎠ ⎝3⎠ ⎝2⎠ 2 4 O čemu treba voditi računa? Treba paziti na zapis: (−5) 2 = (−5)(−5) = 25 , dok − 52 = −5 ⋅ 5 = −25 . Uopšteno važi: (− a) paran = a paran (− a) neparan = − a neparan Dakle, paran izložilac ‘’uništi’’ minus. www.matematiranje.com 1
  • 2.
    ZADACI ( 27 : 25 ) ⋅ 23 1) Izračunati: 24 : 22 (27 : 25 ) ⋅ 23 27 −5 ⋅ 23 22 ⋅ 23 22+3 25 = = = 2 = 2 = 25 − 2 = 23 = 8 24 : 22 24 − 2 22 2 2 _____________________________________________________________ 35 ⋅ 93 2) Izračunati: 27 2 ⋅ 3 35 ⋅ 93 35 ⋅ (32 )3 35 ⋅ 36 35 = 3 2 1 = 6 1 = 1 = 35−1 = 34 = 3 ⋅ 3 ⋅ 3 ⋅ 3 = 81 27 ⋅ 3 (3 ) ⋅ 3 2 3 ⋅3 3 ______________________________________________________________ ( x 4 )3 ⋅ x 3 : x 5 3) Izračunati: = ( x 5 : x 2 )3 ( x 4 ) 3 ⋅ x 3 : x 5 x12 ⋅ x 3 : x 5 x12+ 3−5 x10 = = 3 3 = 9 = x10−9 = x1 = x ( x 5 : x 2 )3 ( x 5− 2 ) 3 (x ) x _______________________________________________________________ 3n +1 ⋅ 3n + 2 4) Izračunati: 32 n + 4 3 n +1 ⋅ 3 n + 2 3 n +1+ n + 2 3 2 n + 3 = 2 n + 4 = 2 n + 4 = Pazi pa zagrade zbog minusa 32n+ 4 3 3 1 1 = 3( 2 n + 3) −( 2 n + 4 ) = 32 n +3− 2 n − 4 = 3−1 = 1 = 3 3 _______________________________________________________________ www.matematiranje.com 2
  • 3.
    5) Izračunati 0,5−1 + 0,25−2 + 0,125−3 + 0,0625−4 0,5−1 + 0,25−2 + 0,125−3 + 0,0625−4 = −1 −2 −3 −4 ⎛1⎞ ⎛1⎞ ⎛1⎞ ⎛1⎞ ⎜ ⎟ +⎜ ⎟ +⎜ ⎟ +⎜ ⎟ = ⎝2⎠ ⎝4⎠ ⎝8⎠ ⎝ 16 ⎠ 1 2 3 4 ⎛ 2 ⎞ ⎛ 4 ⎞ ⎛ 8 ⎞ ⎛ 16 ⎞ ⎜ ⎟ +⎜ ⎟ +⎜ ⎟ +⎜ ⎟ = ⎝1⎠ ⎝ 2⎠ ⎝1⎠ ⎝ 1 ⎠ 21 + 4 2 + 83 + 16 4 = 2 + 16 + 512 + 65536 = 66066 _________________________________________________________________ 6) Izračunati 1−1 + 2 −2 + 3−3 + (−1) −1 + (−2) −2 + (−3) −3 1−1 + 2 −2 + 3−3 + (−1) −1 + (−2) −2 + (−3) −3 = 1 1 1 1 1 1 + 2+ 3+ + + = 1 2 3 (−1) (−2) (−3) 3 1 2 1 1 1 1 1 1 2 1 1+ + −1+ − = + = = 4 27 4 27 4 4 4 2 _________________________________________________________________ −4 2 −2 ⎛1⎞ ⎛3⎞ ⎛5⎞ 7) Ako je a = 5 ⋅ ⎜ ⎟ ⋅ ⎜ ⎟ i b = 10 3 ⎜ ⎟ 3 nadji a ⋅ b −1 ⎝4⎠ ⎝2⎠ ⎝3⎠ −4 2 4 ⎛1⎞ ⎛3⎞ ⎛4⎞ 3 2 53 ⋅ 44 ⋅ 32 a = 53 ⋅ ⎜ ⎟ ⋅ ⎜ ⎟ = 53 ⋅ ⎜ ⎟ ⋅ 2 = ⎝4⎠ ⎝2⎠ ⎝1⎠ 2 22 53 ⋅ (22 ) 4 ⋅ 32 = 2 = 53 ⋅ (22 )3 ⋅ 32 = 53 ⋅ 26 ⋅ 32 2 −2 2 ⎛ 3 ⎞ 10 ⋅ 3 (5 ⋅ 2)3 ⋅ 32 53 ⋅ 23 ⋅ 32 3 2 ⎛5⎞ b = 10 ⋅ ⎜ ⎟ = 103 ⋅ ⎜ ⎟ = 3 = = = 5 ⋅ 23 ⋅ 32 ⎝ 3⎠ ⎝ 5⎠ 52 52 52 Konačno: izračunati i a ⋅ b −1 1 a ⋅ b −1 = 53 ⋅ 26 ⋅ 32 ⋅ = 52 ⋅ 23 = 25 ⋅ 8 = 200 5⋅ 2 ⋅3 3 2 ______________________________________________________________ www.matematiranje.com 3
  • 4.
    ⎛ ⎛ 5x −5 ⎞ −2 ⎛ y −1 ⎞ −3 ⎞ 8) Izračunati ⎜ ⎜ − 2 ⎟ ⋅ ⎜ −1 ⎟ ⎟ : 10 x 2 y −3 ⎜ ⎜ 2 y ⎟ ⎜ 5x ⎟ ⎟ ⎝⎝ ⎠ ⎝ ⎠ ⎠ ⎛ ⎛ 5 x −5 ⎞ −2 ⎛ y −1 ⎞ −3 ⎞ ⎜⎜ ⎟ ⎜ 2 y − 2 ⎟ ⋅ ⎜ 5 x −1 ⎟ ⎟ : 10 x y = 2 −3 ⎜ ⎟ ⎜ ⎟ ⎝⎝ ⎠ ⎝ ⎠ ⎠ ⎛ 5−2 ⋅ x10 y3 ⎞ ⎜ − 2 4 ⋅ −3 3 ⎟ : 10 x 2 y −3 = ⎜ ⎟ ⎝ 2 ⋅y 5 ⋅x ⎠ (5− 2+3 ⋅ x10−3 ⋅ y 3− 4 ⋅ 2 2 ) : 10 x 2 y −3 = (51 ⋅ x 7 ⋅ y −1 ⋅ 4) : 10 x 2 y −3 = 20 7 − 2 −1−( −3) x y = 2 x 5 y −1+ 3 = 2 x 5 y 2 10 __________________________________________________________ 1 −3 1 − 4 10 + 10 9) Ako je 10 = x 2 2 Odrediti x. 55 ⋅10 −7 1 −3 1 − 4 1 1 10 + 10 + 2 2 = 2000 20000 = Izvučemo gore zajednički 55 ⋅10 −7 55 10000000 1 ⎛ 1⎞ 1 11 11 ⎜1 + ⎟ ⋅ 2000 ⎝ 10 ⎠ 2000 10 = = 20000 = 55 55 55 10000000 10000000 10000000 11⋅10000000 11⋅10000000 10000000 = = = 100 = 102 20000 ⋅ 55 11⋅100000 100000 sada je 10 x = 10 2 , dakle x = 2 ________________________________________________________ 10) a) A ⋅10 −5 = 0,2 ⋅ 0,008 b) B ⋅10 −6 = 0,04 ⋅ 0,006 A ⋅10 −5 = 2 ⋅10 −1 ⋅ 8 ⋅10 −3 B ⋅10 −6 = 4 ⋅10 − 2 ⋅ 6 ⋅10 −3 A ⋅10 −5 = 16 ⋅10 − 4 B ⋅10 −6 = 24 ⋅10 −5 16 ⋅10 − 4 24 ⋅10 −5 A= B= 10 −5 10 −6 A = 16 ⋅10 −4−( −5) B = 24 ⋅10 −5+ 6 A = 16 ⋅10 −4+5 B = 24 ⋅10 A = 16 ⋅10 B = 240 A = 160 4
  • 5.
    Ovde smo koristilizapisivanje realnog broja u sistemu sa osnovnim 10. Ovo je dobra opcija kada je broj ‘’glomazan’’. Primeri: 1) Brzina svetlosti je približno c ≈ 300000000m / s a mi je ‘’lakše’’ zapisujemo c ≈ 3 ⋅108 m / s , 108 -znači da ima 8 nula iza jedinice!!! 1 1 1 2 2) = = ⋅10 −5 = ⋅10 −5 = 2 ⋅10 −1 ⋅10 −5 = 2 ⋅10 −6 500000 5 ⋅10 5 5 10 −5 −5 3) 0,000069 = 6,9 ⋅10 ≈ 7 ⋅10 4) Površina zemlje je 510083000km 2 ali mi zapisujemo ≈ 5 ⋅108 km 2 ⎛ 3a − x 2a − x ax ⎞ a−x 11) Izračunati ⎜ − − 2x ⎟ : x ⎜ 1− a−x 1+ a−x a −1 ⎟ a − a−x ⎝ ⎠ ⎛ 3a − x 2a − x ax ⎞ a−x ⎜ 1− a−x − 1+ a−x − a2x −1 ⎟ : a x − a−x = ⎜ ⎟ ⎝ ⎠ ⎛ 3 2 ⎞ 1 ⎜ ax x ax ⎟ x ⎜ − a − 2x ⎟ : a = 1 ⎜ 1− x 1+ x 1 a −1 ⎟ x 1 a − x ⎝ a a ⎠ a ⎛ 3 2 ⎞ 1 ⎜ x x ax ⎟ ax ⎜ xa − a − ⎟: = ⎜ a −1 a x + 1 a2 x −1 ⎟ a2 x −1 ⎜ x ⎟ ⎝ a ax ⎠ ax ⎛ 3 2 ax ⎞ 1 ⎜ x − x − x ⎟ : 2x = ⎝ a − 1 a + 1 (a − 1)(a + 1) ⎠ a − 1 x 3(a x + 1) − 2(a x − 1) − a x a 2 x − 1 ⋅ = (a x − 1)(a x + 1) 1 3a x + 3 − 2a x + 2 − a x (a − 1)(a + 1) x x ⋅ = (a x − 1)(a x + 1) 1 = 3+ 2 = 5 www.matematiranje.com 5
  • 6.
    ⎛ x −x −2 x − x −1 ⎞ 1 − x −1 12) Izračunati ⎜ x + x −1 + 1 1 + x − 2 + 2 ⋅ x −1 ⎟ : 1 + x −1 ⎜ −2 − ⎟ ⎝ ⎠ ⎛ x − x −2 x − x −1 ⎞ 1 − x −1 ⎜ −2 −1 − −2 −1 ⎟ : −1 = ⎝ x + x +1 1+ x + 2 ⋅ x ⎠ 1+ x ⎛ 1 1 ⎞ 1 ⎜ x − x2 x− x ⎟ 1− x ⎜ 1 1 − : = 1 2⎟ ⎜ 2 + +1 1+ 2 + ⎟ 1+ 1 ⎝x x x x⎠ x ⎛ x3 − 1 x2 − 1 ⎞ x −1 ⎜ ⎟ ⎜ x2 − 2 x ⎟: x = ⎜ 1+ x + x 2 x +1+ 2x ⎟ x +1 ⎜ ⎟ ⎝ x2 x2 ⎠ x ⎛ ( x − 1) ( x 2 + x + 1) x( x − 1) ( x + 1) ⎞ x −1 ⎜ − ⎟: = ⎜ x2 + x + 1 ( x + 1) 2 ⎟ x +1 ⎝ ⎠ ⎛ x − 1 x( x − 1) ⎞ x − 1 ⎜ − ⎟: = ⎝ 1 x +1 ⎠ x +1 ( x − 1)( x + 1) − x( x − 1) x + 1 ⋅ = x +1 x −1 ( x − 1) [ ( x + 1) − x ] x + 1 ⋅ = x +1− x = 1 x +1 x −1 www.matematiranje.com 6
  • 7.
    ⎛ an a −n ⎞ ⎛ a n a −n ⎞ 13) Izračunati A = ⎜ + ⎟−⎜ ⎜ 1 − a −n 1 + a −n ⎟ ⎜ 1 + a −n 1 − a −n ⎟ + ⎟ ⎝ ⎠ ⎝ ⎠ ⎛ a n a −n ⎞ ⎛ a n a −n ⎞ A=⎜ −n + − −n ⎟ ⎜ −n + −n ⎟ ⎝ 1− a 1+ a ⎠ ⎝ 1+ a 1− a ⎠ ⎛ 1 ⎞ ⎛ 1 ⎞ ⎜ an n ⎟ ⎜ an n ⎟ A=⎜ + a ⎟−⎜ + a ⎟ ⎜ 1 − 1n 1 + 1n ⎟ ⎜ 1 + 1n 1 − 1n ⎟ ⎝ a a ⎠ ⎝ a a ⎠ ⎛ a n 1 ⎞ ⎛ 1 ⎞ ⎜ ⎟ ⎜ an ⎟ A = ⎜ n1 + n n a ⎟−⎜ + nan ⎟ ⎜ a −1 a +1 ⎟ ⎜ a +1 a −1 ⎟ n ⎜ n ⎟ ⎜ n ⎟ ⎝ a an ⎠ ⎝ a an ⎠ ⎛ a 2n 1 ⎞ ⎛ a 2n 1 ⎞ A=⎜ n + n ⎟−⎜ n + n ⎟ ⎝ a −1 a +1 ⎠ ⎝ a +1 a −1 ⎠ a 2 n (a n + 1) + 1(a n − 1) a 2 n (a n − 1) + 1(a n + 1) A= − (a n − 1)(a n + 1) (a n + 1)(a n − 1) a 3n + a 2 n + a n − 1 − (a 3n − a 2 n + a n + 1) A= (a n − 1)(a n + 1) a 3n + a 2 n + a n − 1 − a 3n + a 2 n − a n − 1 A= (a n − 1)(a n + 1) 2a 2 n − 2 2(a 2 n − 1) 2(a n − 1)(a n + 1) A= = n = n =2 (a n − 1)(a n + 1) (a − 1)(a n + 1) (a − 1)(a n + 1) www.matematiranje.com 7