Đáp án: `a ) ( x + 1 )(x-3)`
` b ) ( x ^2 + 1 ) ( x^ 2 + 1 + x )`
Giải thích các bước giải:
`a ) x^ 2 − 2 x − 3`
`= x^ 2 + x − 3 x − 3`
`= (x^2 + x ) − ( 3x+ 3 )`
`= x(x+1 ) −3 ( x+ 1 )`
`= ( x + 1 )( x − 3 ) `
`b ) x ^4 + x ^3 + 2 x ^2 + x + 1`
`= ( x ^4 + 2 x ^2 + 1 ) + ( x^ 3 + x )`
`= [( x ^2)^4 + 2. x ^2. + 1^4 )] + ( x^ 3 + x )`
`= ( x^ 2 + 1 ) ^2 + x ( x^ 2 + 1 )`
`= ( x ^2 + 1 ) ( x^ 2 + 1 + x )`