x^2+x-2=0,x^3+3x^2+2004=?

来源:百度知道 编辑:UC知道 时间:2024/06/18 18:01:11

x^3+3x^2+2004
=x(x^2+x-2)+2x^2+2x+2004
=x*0+2(x^2+x-2)+2008
=2*0+2008
=2008.

x^2+x-2=0,那么(x+2)(x-1)=0
x=1或者-2
那么x^3+3x^2+2004=2008

x^2+x-2=0
=> (x+2)(x-1)=0
=> x=-2或1
当x=-2
x^3+3x^2+2004 = -8 + 12 +2004 =2008
当x=1
x^3+3x^2+2004 = 1 + 3 + 2004 =2008

x^2+x-2=0
x^2+x=2

x^3+3x^2+2004
=x^3+x^2+2x^2+2004
=x(x^2+x)+2x^2+2004
=2x+2x^2+2004
=2(x^2+x)+2004
=2*2+2004
=2008

由x^2+x-2=0,解得x=1或x=-2,当x=1时,x^3+3x^2+2004=2008,当x=-2时,x^3+3x^2+2004=1999

2008