Tìm x

a;1/2x +4/5.(x+2)=15/4

b;56/3-(1,73x + 3,27x)=71/4

c;1/3.|x-2|-3/7=4/5

d,|x| +1/2=2

e,2/5-x+2x=3/-4

f,1/3.|x-2| - 3/7=4/5

g,2.|1/2x-1/3|-3/2=1/4

h,3/4-2.|2x-2/3|=2

i,-5.(x+1/5)-1/2.(x-2/3)=3/2x-5/6

k,3.(x-1/2)-5.(x+3/5)= -x+1/5

Helpp anh chị ơi giúp e vs ạ.Ai lm nhanh+đúng e vote 5*+ctlhn aa.E c.ơn anh chị trc ạ.

Đáp án+Giải thích các bước giải:

 `a)`

`1/2 x+4/5. (x+2)=15/4`

`=>1/2 x+ 4/5 x +8/5=15/4`

`=>x.(1/2+4/5)=15/4-8/5`

`=>x.(5/10+8/10)=43/20`

`=>x. 13/10=43/20`

`=>x=43/20: 13/10`

`=>x=43/26`

Vậy `x=43/26`

`b)`

`56/3-(1,73x+3,27x)=71/4`

`=>x.(1,73+3,27)=56/3-71/4`

`=>x. 5=\frac{224}{12}-\frac{213}{12}`

`=>x. 5=11/12`

`=>x=11/12:5`

`=>x=11/60`

Vậy `x=11/60`

`c),f)`

`1/3.|x-2|-3/7=4/5`

`=>1/3.|x-2|=4/5+3/7`

`=>1/3.|x-2|=28/35+15/35`

`=>1/3.|x-2|=43/35`

`=>|x-2|=43/35:1/3`

`=>|x-2|=\frac{129}{35}`

`=>x-2=\frac{129}{35}` hoặc `x-2=-\frac{129}{35}`

`=>x=\frac{129}{35}+2` hoặc `x=-\frac{129}{35}+2`

`=>x=\frac{199}{35}` hoặc `x=-\frac{59}{35}`

Vậy `x\in{\frac{199}{35};-59/35}`

`d)`

`|x|+1/2=2`

`=>|x|=2-1/2`

`=>|x|=4/2-1/2`

`=>|x|=3/2`

`=>x=3/2` hoặc `x=-3/2`

Vậy `x\in{3/2;-3/2}`

`e)`

`2/3-x+2x=3/-4`

`=>2x-x=-3/4-2/3`

`=>x.(2-1)=-9/12-8/12`

`=>x=-17/12`

Vậy `x=-17/12`

`f)`

`1/3.|x-2|-3/7=4/5` (đề giống câu `c` nên mình chỉ làm một lần)

 `->x\in{\frac{199}{35};-59/35}`

Vậy `x\in{\frac{199}{35};-59/35}`

`g)`

`2.|1/2x-1/3|-3/2=1/4`

`=>2.|1/2x-1/3|=1/4+3/2`

`=>2.|1/2x-1/3|=7/4`

`=>|1/2x-1/3|=7/4:2`

`=>|1/2x-1/3|=7/8`

`=>1/2x-1/3=7/8` hoặc `1/2x-1/3=-7/8`

`=>1/2x=7/8+1/3` hoặc `1/2x=-7/8+1/3`

`=>1/2x=29/24` hoặc `1/2x=-13/24`

`=>x=29/24: 1/2` hoặc `x=(-13/24):1/2`

`=>x=29/12` hoặc `x=-13/12`

Vậy `x\in{19/12;-13/12}`

`h)`

`3/4 -2.|2x-2/3|=2`

`=>2.|2x-2/3|=3/4-2`

`=>2.|2x-2/3|=-5/4`

`=>|2x-2/3|=-5/4:2`

`=>|2x-2/3|=-5/8` (Vô lí)

Vì: `|2x-2/3|\ge0AAx`

Mà `-5/8<0`

`->` Không có giá trị `x` thoả mãn.

Vậy không có giá trị `x` thoả mãn.

`i)`

`-5.(x+1/5)-1/2.(x-2/3)=3/2x-5/6`

`=>-5x-1-1/2x+1/3=3/2x-5/6`

`=>x.(-5-1/2)+(1/3-1)-3/2x=-5/6`

`=>x.(-5-1/2-3/2)-2/3=-5/6`

`=>x.(-5-2)=-5/6+2/3`

`=>x.(-7)=-5/6+4/6`

`=>x.(-7)=-1/6`

`=>x=(-1/6):(-7)`

`=>x=1/42`

Vậy `x=1/42`

`k)`

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

`=>3x-3/2-5x-3+x=1/5`

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

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

`=>-x=2/10+15/10+30/10`

`=>-x=47/10`

`=>x=-47/10`

Vậy `x=-47/10`