分解因式：x^3-7x+6=
2个回答
x"' - 7x + 6
= x"' - x - 6x + 6
= x( x" - 1 ) - 6( x - 1 )
= x( x + 1 )( x - 1 ) - 6( x - 1 )
= ( x - 1 )( x" + x - 6 )
= ( x - 1 )( x" + 3x - 2x - 6 )
= ( x - 1 )[ x( x + 3 ) - 2( x + 3 ) ]
= ( x - 1 )( x - 2 )( x + 3 )
或者
= x"' - 1 - 7x + 6 + 1
= ( x"' - 1 ) - 7x + 7
= ( x - 1 )( x" + x + 1 ) - 7( x - 1 )
= ( x - 1 )( x" + x + 1 - 7 )
= ( x - 1 )( x" - 2x + 3x - 6 )
= ( x - 1 )[ x( x - 2 ) + 3( x - 2 ) ]
= ( x - 1 )( x - 2 )( x + 3 )
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