Giải thích các bước giải:
`a, \ (x-2)(x+2)-(x-3)^2=9`
`<=> x^2-4-(x^2-6x+9)=9`
`<=> x^2-4-x^2+6x-9=9`
`<=> (x^2-x^2)+6x=9+9+4`
`<=> 6x=22`
`<=> x=11/3`
Vậy `x=11/3`
`b, \ (x-1)(x^2+1)-(x+1)(x^2-x+1)=x(2-x)`
`<=> x^3+x-x^2-1-(x^3+1)=2x-x^2`
`<=> x^3-x^2+x-1-x^3-1+x^2-2x=0`
`<=> (x^3-x^3)+(x^2-x^2)+(x-2x)=1+1`
`<=> -x=2`
`<=> x=-2`
Vậy `x=-2`
`c, \ (x-3)(x^2+3x+9)+x(x+2)(2-x)=1`
`<=> x^3-27-x(x^2-4)=1`
`<=> x^3-27-x^3+4x=1`
`<=> (x^3-x^3)+4x=1+27`
`<=> 4x=28`
`<=> x=7`
Vậy `x=7`
`d, \ (x+1)^3-(x-1)^3-6(x-1)^2=-19`
`<=> x^3+3x^2+3x+1-(x^3-3x^2+3x-1)-6(x^2-2x+1)=-19`
`<=> x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+12x-6=-19`
`<=> (x^3-x^3)+(3x^2+3x^2-6x^2)+(3x-3x+12x)=-19+6-1-1`
`<=> 12x=-15`
`<=> x=-5/4`
Vậy `x=-5/4`
