`(x+2)(x+3)-(x-2)(x-5)=-4`
⇔` (x²+3x+2x+6)` `-``( x²-5x-2x+10) ``=-4`
`⇔` `x² +5x +6 - x²+7x -10 +4=0`
`⇔` `12x=0`
`⇔ ` `x=0`
Vậy `x=0`
`(x+1)( x² -x+1)-x(x+3)(x-3)=8`
`⇔` `(x³+1)³` `-x(x²-9) =8`
`⇔` `x³ +1 -x³ +9x-8=0`
`⇔` `9x -7=0`
`⇔` `9x=7`
`⇔`` x=``7/9`
Vậy `x=``7/9`
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