Tìm x : a/ 7/2 . ( x – 1 ) + 4/3 = 5/7 b/ 1/2 . ( x – 1/3 ) + 1/2 . (x + 2/3 ) = 1/4 c/ 4/3 . ( x – 1/2 ) = 1/2 . ( x + 1/3 ) d/ 3/4 . ( x

Đáp án:

Giải thích các bước giải:

 a)  7/2 . ( x – 1 ) + 4/3 = 5/7

⇔ 7/2.(x-1)=5/7-4/3

      7/2.(x-1)=-13/21

           x-1=-13/21÷7/2

           x-1=-26/147

          x= -26/147+1

          x=-173/147

b)    1/2 . ( x – 1/3 ) + 1/2 . (x + 2/3 ) = 1/4

⇔  1/2.x-1/6+1/2.x+1/3=1/4

  x=1/4-1/3+1/6

 x=1/12

c)    4/3 . ( x – 1/2 ) = 1/2 . ( x + 1/3 )

       4/3.x-2/3=1/2.x+1/6

    4/3.x-1/2.x=1/6+2/3

        x.(4/3-1/2)=5/6

     x.5/6=5/6

  x=5/6÷5/6=1

d)        3/4 . ( x + 1/2 ) -1/3 = 1/2 x

           3/4.x+3/8-1/3=1/2.x

          3/4.x-1/2.x=1/3-3/8

          1/4.x=-1/24

             x=-1/24÷1/4=-1/6