Đáp án+Giải thích các bước giải:

`5/3+1/3(x+1/2)=4`

`=>1/3(x+1/2)=4-5/3`

`=>1/3(x+1/2)=7/3`

`=>x+1/2=7`

`=>x=7-1/2=13/2`

Vậy `x=13/2`.

`(x+1)/10+(x+9)/2+(x+2)/9=(x+8)/3+(x+7)/4+(x+5)/6`

`=>(x+1)/10+1+(x+9)/2+1+(x+2)/9+1=(x+8)/3+1+(x+7)/4+1+(x+5)/6+1`

`=>(x+11)/10+(x+11)/2+(x+11)/9=(x+11)/3+(x+11)/4+(x+11)/6`

`=>(x+11)(1/10+1/2+1/9-1/3-1/4-1/6)=0`

Do `1/10+1/2+1/9-1/3-1/4-1/6 ne 0`

`=>x+11=0`

`=>x=-11`

Vậy `x=-11.`

Câu cuối thiếu đề.

`5/3 + 1/3 .(x + 1/2) =4`

`          1/3. (x + 1/2) = 4 - 5/3`

`          1/3 . (x + 1/2)= 7/3`

`                   x + 1/2 = 7/3 : 1/3`

`                   x + 1/2 = 7`

`                   x           = 7 - 1/2`

`                   x           = 13/2`

Vậy `x = 13/2`

`x+1/10 + x+9/ 2 + x+2/9 = x+8/3 + x+7/4 + x+5/6`

`x+1/10 +1+ x+9/ 2 +1+ x+2/9 +1 = x+8/3+1 + x+7/4+1 + x+5/6+1`

`x+1/10 + 10/10+ x+9/ 2 +2/2 + x+2/9 + 9/9 = x+8/3 + 3/3 + x+7/4 +4/4 + x+5/6 + 6/6`

`x+11/10 + x+11/ 2 + x+11/9  = x+11/3 + x+11/4 + x+11/6`

`x+11/10 + x+11/ 2 + x+11/9 - x+11/3 - x+11/4 - x+11/6 = 0`

`=> (x+11).(1/10+1/2+1/9-1/3-1/4-1/6) =0`

Vì `1/10 + 1/2 + 1/9 - 1/3 - 1/4 - 1/6`$\ne$ `0`

`=> x + 11 = 0`

`=> x         = 0 - 11`

`=> x         = -11`

Vậy `x = - 11`