Treść zadania

Najlepsze rozwiązanie

• 

  0 0

  sonar 7.4.2011 (23:41)

  zad8.
  a)
  [x+ (x+7)] :2= 20 /*2
  x+ (x+7) = 40
  x+x+7 = 40
  2x= 40 -7
  2x= 33
  x= 33 : 2
  x= 16,5
  
  spr.
  (16,5 + 16,5 + 7 ) :2= 20
  40 :2= 20
  20 + 20
  L=P
  
  
  b)
  (y + 3y + y+10) :3= 16 /*3
  5y + 10 = 48
  5y = 48 -10
  5y = 38
  y = 38 :5
  y= 7,6
  
  spr.
  (y + 3y + y+10) :3= 16
  (7,6 + 3*7,6 + 7,6 + 10) :3= 16
  (7,6 + 22,8 + 17,6) : 3= 16
  48 : 3= 16
  16 = 16
  L=P
  
  
  c)
  15 +y = 51 -y
  y+y = 51 - 15
  2y = 36
  y = 36 :2
  y= 18
  
  
  spr.
  15 +y = 51 -y
  15 + 18 = 51 - 18
  33 = 33
  L=P
  
  
  zad9.
  a)
  1/3x -2 = x+2 /*3
  x - 6 = 3x +6
  x - 3x = 6 +6
  -2x = 12
  x= 12 : (-2)
  x= -6
  
  spr.
  1/3x -2 = x+2
  1/3 * (-6) -2 = -6 +2
  -6/3 -2= -4
  - 2 -2= -4
  -4=-4
  L=P
  
  
  b)
  1- 6/7x= 4/7 /*7
  7 - 6x = 4
  -6x = 4 - 7
  -6x= -3
  x= -3 : (-6)
  x= 3/6
  x=1/2
  
  
  spr.
  1- 6/7x= 4/7
  1 - 6/7 * 1/2 = 4/7
  1 - 3/7 * 1/1 = 4/7
  1 - 3/7 = 4/7
  4/7 = 4/7
  L=P
  
  c)
  6(1/4x -2) = 18 /:6
  1/4x -2 = 3 /*4
  x- 8 = 12
  x= 12 +8
  x= 20
  
  spr.
  6(1/4x -2) = 18
  6 ( 1/4 * 20 - 2) = 18
  6( 20/4 -2) = 18
  6 (5-2) = 18
  6 * 3= 18
  18 = 18
  L=P
  
  
  d)
  x/6 - 1/6 = 1 /*6
  x- 1 = 6
  x= 6 + 1
  x= 7
  
  
  spr.
  x/6 - 1/6 = 1
  7/6 - 1/6 = 1
  6/6 =1
  1=1
  L=P
  
  
  e)
  -2(2x -1) = x/3 /*3
  -6( 2x -1) = x
  -12x + 6 = x
  - 12x - x = -6
  -13x = -6
  x= -6 : (-13)
  x= 6/13
  
  spr.
  -2(2x -1) = x/3
  -2 ( 2 * 6/13 -1) = 6/13 : 3
  -2 ( 12/13 - 1) = 6/13 * 1/3
  -2 * (-1/13) = 2/13 * 1/1
  2/13 = 2/13
  L =P
  
  
  f)
  2/3 (3 -x) = -2 / :2/3
  3 -x = -2 : 2/3
  3-x = - 2 * 3/2
  3-x = - 6/2
  -x = - 6/2 -3
  -x = -3 -3
  -x = -6 /*(-1)
  x= 6
  
  
  spr.
  2/3 (3 -x) = -2
  2/3 ( 3 - 6) = -2
  2/3 * (-3) = -2
  - 6/3 = -2
  -2 = -2
  L=P
  
  
  g)
  3/4 (2 - 3x ) = -6 / :3/4
  2 - 3x = -6 : 3/4
  2 - 3x = -6 * 4/3
  2 - 3x = -24/3
  2 - 3x = -8
  -3x = -8 -2
  -3x = - 10
  x= -10 : (-3)
  x= 3 i 1/3
  
  
  spr.
  3/4 (2 - 3x ) = -6
  3/4 ( 2 - 3 *3 i 1/3 ) = -6
  3/4 * ( 2 - 10) = -6
  3/4 * (-8) = -6
  -24/4 = -6
  -6 = -6
  L=P
  
  h)
  1/5(x - 3) = 9 -x /*5
  x- 3 = 45 - 5x
  x + 5x = 45 + 3
  6x = 48
  x= 48 : 6
  x= 8
  
  spr.
  1/5(x - 3) = 9 -x
  1/5 ( 8 - 3) = 9 - 8
  1/5 * 5 = 1
  5/5 = 1
  1=1
  L=P
  
  
  i)
  0,6+x/2 = x + 1 /*2
  0,6 + x = 2x + 2
  x - 2x = 2 - 0,6
  -x = 1,4 /*(-1)
  x= - 1,4
  
  
  spr.
  0,6+x/2 = x + 1
  0,6 + (-1,4)/2 = -1,4 +1
  0,6-1,4/2 = -0,4
  -0,8/2 = -0,4
  -0,4 = -0,4
  L=P

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