Tìm x , biết : 1) 1/4 + 3/4.x = 1/2 2) x/5 +x/10=2/5 3)x-2/3 = 5/7 4) 2.x – 1 / 6 = x-3/2 5) ( 75% . x – 2/3 ) = 1/6

0 bình luận về “Tìm x , biết : 1) 1/4 + 3/4.x = 1/2 2) x/5 +x/10=2/5 3)x-2/3 = 5/7 4) 2.x – 1 / 6 = x-3/2 5) ( 75% . x – 2/3 ) = 1/6”

1. 1)1/4 + 3/4.x = 1/2

                3/4.x = 1/2-1/4

                3/4.x – 1/4

                x = 1/4:3/4

               x=1/3

   2)x/5 +x/10=2/5

   2x/10+x/10=4/10

   =>3x=4

     x=4/3

   3)x-2/3 = 5/7

      x =5/7+2/3

      x=29/21

   4)2.x – 1 / 6 = x-3/2

     2.x=x-3/2+1/6

    2.x=x-5/3

   =>x-2x=5/3

   =>-x=5/3

   =>x=-5/3

   5) ( 75% . x – 2/3 ) = 1/6

   3/4.x-2/3=1/6

   3/4-x=1/6+2/3

   3/4.x=5/6

   x=5/6:3/4

   x=10/9

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2. Đáp án + giải thích bước giải :

   `1) 1/4 + 3/4x = 1/2`

   `-> 3/4x = 1/2 – 1/4`

   `-> 3/4x = 1/4`

   `-> x = 1/4 : 3/4`

   `-> x = 1/3`

   Vậy `x = 13`

   `2) x/5 + x/10 = 2/5`

   `->x . (1/5 + 1/10) = 2/5`

   `-> x . 3/10 = 2/5`

   `-> x = 2/5 : 3/10`

   `-> x = 4/3`

   Vậy `x = 4/3`

   `3) x – 2/3 = 5/7`

   `-> x = 5/7 + 2/3`

   `-> x = 29/21`

   Vậy `x = 29/21`

   `4) 2x – 1/6  = x – 3/2`

   `-> 2x – x = 1/6 – 3/2`

   `-> (2 – 1)x = (-4)/3`

   `-> x = (-4)/3`

   Vậy `x = (-4)/3`

   `5) (75%x – 2/3) = 1/6`

   `-> 3/4x = 1/6 + 2/3`

   `-> 3/4x = 5/6`

   `-> x = 5/6 : 3/4`

   `-> x = 10/9`

   Vậy `x = 10/9`

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