`@` tremamnon

Đáp án:

`a)`

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

`to 2x^2-3x-4x+6-2x^2-x-6=0`

`to (2x^2-2x^2)-(3x+4x+x)+(6-6)=0`

`to -8x=0`

`to x=0`

Vậy `x=0`

`b)`

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

`to (10x-5)(x+2)-2(5x-3)(x+2)=5`

`to (x+2)[(10x-5)-2(5x-3)]=5`

`to (x+2)[(10x-5)+(-10x+6)]=5`

`to (x+2)[10x-5-10x+6]=5`

`to (x+2)[(10x-10x)-(5-6)]=5`

`to (x+2)*1=5`

`to x+2=5:1=5`

`to x=5-2=3`

Vậy `x=3`

`c)`

`2x^2+3(x-2)(x+2)-5x(x+3)=0`

`to 2x^2+(3x-6)(x+2)-5x^2-15x=0`

`to 2x^2+3x^2+6x-6x-12-5x^2-15x=0`

`to (2x^2+3x^2-5x^2)+(6x-6x+15x)-12=0`

`to 15x-12=0`

`to 15x=0+12=12`

`to x=12:15=-4/5`

Vậy `x=-4/5`

`d)`

`(7-3x)(x+2)+3(x-2)(x+1)+2(3x-2)(x+2)=0`

`to (x+2)[(7-3x)+2(3x-2)]+3(x-2)(x+1)=0`

`to (x+2)[7-3x+6x-4]+3(x-2)(x+1)=0`

`to (x+2)[(7-4)-(3x-6x)]+(3x-6)(x+1)=0`

`to (x+2)[3+3x]+(3x-6)(x+1)=0`

`to 3x+3x^2+6+6x+3x^2+3x-6x-6=0`

`to (3x+6x+3x-6x)+(3x^2+3x^2)+(6-6)=0`

`to 6x+6x^2=0`

`to x(6+6x)=0`

`TH1: x=0`

`TH2:`

`6+6x=0`

`to 6x=0-6=-6`

`to x=(-6):6=-1`

Vậy `x in {0;-1}`