已知x^2-3x+1=0,求2x^3-3x^2-7x+2009

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已知x^2-3x+1=0,求2x^3-3x^2-7x+2009

已知x^2-3x+1=0,求2x^3-3x^2-7x+2009
已知x^2-3x+1=0,求2x^3-3x^2-7x+2009

已知x^2-3x+1=0,求2x^3-3x^2-7x+2009
2x^3-3x^2-7x+2009
=2x^3-6x^2+3x^2-7x+2009
=2(x^3-3x^2+x)-2x+3x^2-7x+2009
=2x(x^2-3x+1)+3x^2-9x+2009
=2x(x^2-3x+1)+3(x^2-3x+1)-3+2009
=0+0+2006=2006

2000或1992

收起

2x^3-3x^2-7x+2009=2x(x^2-3x+1)+3x^2-9x+2009=2x*0+3x^2-9x+2009=3x^2-9x+2009=3(x^2-3x+1)+2006=3*0+2006=2006

2x^3-3x^2-7x+2009
=2x^3-6x^2+2x+3x^2-9x+2009
=2x(x^2-3x+1)+3x^2-9x+2009
=2x*0+3x^2-9x+2009
=3x^2-9x+2009
=3(x^2-3x+1)+2006
=3*0+2006
=2006