Tìm X a)(X-2)^2-(X+3).(X-3)=1 b)(X+2)^3-X^2.(X+6)=4 c)(X+5)^2-(X+2).(X-3)=4 d)(X+3)^2-(X+4).(X-1)=7 e)(X-1)^2+(2X+1)^2-3.(X-1).(1+x)=5 5*+ctlhn ạ

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

`=>x^2-4x+4-x^2+9=1`

`=>(x^2-x^2)-4x+(4+9)=1`

`=>-4x+13=1`

`=>-4x=1-13`

`=>-4x=-12`

`=>x=-12:(-4)`

`=>x=3`

Vậy `x=3`

`b)` `(x+2)^3-x^2(x+6)=4`

`=>x^3+6x^2+12x+8-x^3-6x^2=4`

`=>(x^3-x^3)+(6x^2-6x^2)+12x+8=4`

`=>12x=4-8`

`=>12x=-4`

`=>x=-4:12`

`=>x=(-1)/3`

Vậy `x=(-1)/3`

`c)` `(x+5)^2-(x+2)(x-3)=4`

`=>x^2+10x+25-(x^2-3x+2x-6)=4`

`=>x^2+10x+25-x^2+3x-2x+6=4`

`=>(x^2-x^2)+(10x+3x-2x)+(25+6)=4`

`=>11x+31=4`

`=>11x=4-31`

`=>11x=-27`

`=>x=(-27)/11`

Vậy `x=(-27)/11`

`d)` `(x+3)^2-(x+4)(x-1)=7`

`=>x^2+6x+9-(x^2-x+4x-4)=7`

`=>x^2+6x+9-x^2+x-4x+4=7`

`=>(x^2-x^2)+(6x+x-4x)+(9+4)=7`

`=>3x+13=7`

`=>3x=7-13`

`=>3x=-6`

`=>x=-6:3`

`=>x=-2`

Vậy `x=-2`

`e)` `(x-1)^2+(2x+1)^2-3(x-1)(1+x)=5`

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

`=>x^2-2x+1+4x^2+4x+1-3x^2+3=5`

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

`=>2x^2+2x+5=5`

`=>2x^2+2x+5-5=0`

`=>2x^2+2x=0`

`=>2x(x+1)=0`

`=>` $\left[ \begin{array}{l}2x=0\\x+1=0\end{array} \right.$ 

`=>` $\left[ \begin{array}{l}x=0\\x=-1\end{array} \right.$ 

Vậy `x\in{0;-1}`