`text{Bài 4:}`

`a)` `5-(x-6)=4(3-2x)`

`5-x+6=12-8x`

`-x+8x=12-11`

`7x=1`

`x=1/7`

`b)` `(x+1)(2x-3)=(2x-1)(x+5)`

`2x^2-3x+2x-3=2x^2+10x-x-5`

`-x-3=9x-5`

`-x-9x=-5+3`

`-10x=-2`

`x=1/5`

`c)` `(x-2)^3+(3x-1)(3x+1)=(x+1)^3`

`(x^3-6x^2+12x-8)+(9x^2-1)=x^3+3x^2+3x+1`

`x^3+3x^2=x^3+3x^2+3x+1`

`12x-3x=1+9`

`9x=10`

`x=10/9`

`d)` `(x+1)(x^2-x+1)-2x=x(x-1)(x+1)`

`(x^3+1)-2x=x(x^2-1)`

`x^3-2x+1=x^3-x`

`-2x+x=-1`

`-x=-1`

`x=1`

`text{Bài 5:}`

`a)` `(x+4)/4-(x-3)/6=x/3`

`3(x+4)-2(x-3)=4x`

`3x+12-2x+6=4x`

`x+18=4x`

`x-4x=-18`

`-3x=-18`

`x=6`

`b)` `(3x-2)/6-5=(3-2(x+7))/4`

`2(3x-2)-60=3[3-2(x+7)]`

`6x-4-60=9-6(x+7)`

`6x-64=9-6x-42`

`6x+6x=-33+64`

`12x=31`

`x=31/12`

`c)` `(x+5)/4-(2x-3)/3=(6x-1)/3+(2x-1)/12`

`3(x+5)-4(2x-3)=4(6x-1)+(2x-1)`

`3x+15-8x+12=24x-4+2x-1`

`-5x+27=26x-5`

`31x=32`

`x=32/21`

`d)` `(2x-8)/6-(3x+1)/4=(9x-2)/8+(3x-1)/12`

`4(2x-8)-6(3x+1)=3(9x-2)+2(3x-1)`

`8x-32-18x-6=27x-6+6x-2`

`-10x-38=33x-8`

`-10x-33x=-8+38`

`-43x=30`

`x=-30/43`