Bài 1: tìm x biết

a) (x + 2)²-x(x+3)=2

b) (x+2)(x-2)-(x+1)²=7

c) 6x²-(2x + 1)(3x-2) =1

d) (x+2)(x+3) - (x-2)(x+1) =2

e) 6(x-1)(x+1)-(2x-1)(3x+2)+3=0

f) x(3x+1)+(x-1)²-(2x+1)(2x-1)=0

g) (x+1)^3+(2-x)^3-9(x-3)(x+3)=0

) (x-1)^3-(x+3)(x²-3x+9)+3x²=25

k) (x+2)^3-(x+1)(x²-x+ 1)-6(x-1)²=23

Giải giúp mk với mk cần gấp

Đáp án+Giải thích các bước giải:

 `a)`

`(x+2)^{2}-x.(x+3)=2`

`<=>x^{2}+2.x.2+2^{2}-x^{2}-3x=2`

`<=>x^{2}+4x+4-x^{2}-3x=2`

`<=>x+4=2`

`<=>x=-2`

Vậy `x=-2`

`b)`

`(x+2).(x-2)-(x+1)^{2}=7`

`<=>x^{2}-2^{2}-(x^{2}+2x+1)=7`

`<=>x^{2}-4-x^{2}-2x-1=7`

`<=>-2x-5=7`

`<=>-2x=12`

`<=>x=-6`

Vậy `x=-6`

`c)`

`6x^{2}-(2x+1).(3x-2)=1`

`<=>6x^{2}-(6x^{2}-4x+3x-2)=1`

`<=>6x^{2}-6x^{2}+4x-3x+2=1`

`<=>x+2=1`

`<=>x=-1`

Vậy `x=-1`

`d)`

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

`<=>x^{2}+3x+2x+6-(x^{2}+x-2x-2)=2`

`<=>x^{2}+5x+6-x^{2}+x+2=2`

`<=>6x+8=2`

`<=>6x=-6`

`<=>x=-1`

Vậy `x=-1`

`e)`

`6.(x-1).(x+1)-(2x-1).(3x+2)+3=0`

`<=>6.(x^{2}-1^{2})-(6x^{2}+4x-3x-2)+3=0`

`<=>6x^{2}-6-6x^{2}-x+2+3=0`

`<=>-x-1=0`

`<=>-x=1`

`<=>x=-1`

Vậy `x=-1`

 `f)`

`x.(3x+1)+(x-1)^{2}-(2x+1).(2x-1)=0`

`<=>3x^{2}+x+(x^{2}-2x+1)-[(2x)^{2}-1^{2}]=0`

`<=>3x^{2}+x+x^{2}-2x+1-(4x^{2}-1)=0`

`<=>4x^{2}-x+1-4x^{2}+1=0`

`<=>-x+2=0`

`<=>-x=-2`

`<=>x=2`

Vậy `x=2`

`g)`

`(x+1)^{3}+(2-x)^{3}-9.(x-3).(x+3)=0`

`<=>(x+1+2-x).[(x+1)^{2}-(x+1).(2-x)+(2-x)^{2}]-9.(x^{2}-3^{2})=0`

`<=>3.[x^{2}+2x+1+x^{2}-4x+4-(2x-x^{2}+2-x)]-9.(x^{2}-9)=0`

`<=>3.(2x^{2}-2x+5-2x+x^{2}-2+x)-9x^{2}+81=0`

`<=>3.(3x^{2}-3x+3)-9x^{2}+81=0`

`<=>9x^{2}-9x+9-9x^{2}+81=0`

`<=>-9x+90=0`

`<=>-9x=-90`

`<=>x=10`

Vậy `x=10`

`h)`

`(x-1)^{3}-(x+3).(x^{2}-3x+9)+3x^{2}=25`

`<=>x^{3}-3x^{2}+3x-1-(x+3).(x^{2}-x.3+3^{2})+3x^{2}=25`

`<=>x^{3}+3x-1-(x^{3}+3^{3})=25`

`<=>x^{3}+3x-1-x^{3}-27=25`

`<=>3x-28=25`

`<=>3x=53`

`<=>x=53/3`

Vậy `x=53/3`

`k)`

`(x+2)^{3}-(x+1).(x^{2}-x+1)-6.(x-1)^{2}=23`

`<=>x^{3}+3.x^{2}.2+3.x.2^{2}+2^{3}-(x+1).(x^{2}-x.1+1^{2})-6.(x^{2}-2x+1)=23`

`<=>x^{3}+6x^{2}+12x+8-(x^{3}+1^{3})-6x^{2}+12x-6=23`

`<=>x^{3}+24x+2-x^{3}-1=23`

`<=>24x+1=23`

`<=>24x=22`

`<=>x=11/12`

Vậy `x=11/12`