Toán Lớp 6: ( x – 1/2 ) + ( x – 1/6 )+ ( x – 1/12 ) + ( x – 1/20 ) + – + ( x – 1/90 ) + ( x – 1/110 ) = 12/11

0 bình luận về “Toán Lớp 6: ( x – 1/2 ) + ( x – 1/6 )+ ( x – 1/12 ) + ( x – 1/20 ) + – + ( x – 1/90 ) + ( x – 1/110 ) = 12/11”

1. (x – 1/2) + (x – 1/6) + (x – 1/12) + … + (x – 1/110) = 12/11

   => (x + x + … + x) – (1/2 + 1/6 + 1/12 + … + 1/110) = 12/11

   Ta có:

   1/2 + 1/6 + 1/12 + … + 1/110

   = 1/(1.2) + 1/(2.3) + 1/(3.4) + … + 1/(10.11)

   = 1 – 1/2 + 1/2 – 1/3 + .. + 1/10 – 1/11

   = 1 – 1/11

   = 10/11

   Do đó:

   (x + x + … + x) – (1/2 + 1/6 + 1/12 + … + 1/110) = 12/11

   => 10x – 10/11 = 12/11

   => 10x = 12/11 + 10/11

   => 10x = 22/11

   => x = 1/5

   Vậy x = 1/5

2. Giải đáp+Lời giải và giải thích chi tiết:

    (x -1/2) + ( x – 1/6 )+ ( x – 1/12 ) + ( x – 1/20 ) + …. + ( x – 1/90 ) + ( x – 1/110 ) = 12/11
   => (x + x + … + x) – (1/2 + 1/6 + 1/12 + … + 1/110) = 12/11
   Ta có: 1/2 + 1/6 + 1/12 + … + 1/110
   => = 1/(1.2) + 1/(2.3) + 1/(3.4) + … + 1/(10.11)
   => = 1 – 1/2 + 1/2 – 1/3 + .. + 1/10 – 1/11
   => = 1 – 1/11
   => 10/11 

   Lại có: (x + x + … + x) – (1/2 + 1/6 + 1/12 + … + 1/110) = 12/11

   => 10x – 10/11 = 12/11

   => 10x = 22/11

   => x =1/5

   Vậy x= 1/5

   $@Pipimm~$