`y10000`
`1 ) `
`a³ - 2a² + a - ab²`
`= a . ( a² - 2a + 1 - b² )`
`= a . [ ( a² - 2a + 1 ) - b² ]`
`= a . [ ( a - 1 )² - b² ]`
`= a . ( a - 1 - b ) . ( a - 1 + b )`
`2 )`
`x⁴ - x³ - x² + 1`
`= x³ . ( x - 1 ) - ( x² - 1 )`
`= x³ . ( x - 1 ) - ( x + 1 ) . ( x - 1 )`
`= ( x³ - x + 1 ) . ( x - 1 )`
`3 ) `
`a²x+a²y-7x-7y`
`= a² . ( x + y ) - 7 . ( x + y )`
`= ( a² - 7 ) . ( x + y )`
`Bài 2 :`
`x³+27+(x+3).(x-9)=0`
`<=> x³ + 27 + x² - 9x + 3x - 27 = 0`
`<=> x³ + x² - 6x = 0`
`<=> x . ( x² + x - 6 ) = 0`
`<=> x . ( x - 2 ) .( x + 3 ) = 0`
`<=>` \(\left[ \begin{array}{l}x=0\\x+3=0\\x-2=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=0\\x=-3\\x=2\end{array} \right.\)
