已知x2+x+3=0,求x5+3x4+2x3+2x2-10x的值.
问题描述:
已知x2+x+3=0,求x5+3x4+2x3+2x2-10x的值.
答
∵x2+x+3=0,
∴x2+x=-3,
x5+3x4+2x3+2x2-10x
=x3(x2+x)+2x4+2x3+2x2-10x
=-3x3+2x4+2x3+2x2-10x
=2x4-x3+2x2-10x
=2x2(x2+x)-3x3+2x2-10x
=-3x3-4x2-10x
=-3x(x2+x)-x2-10x
=9x-x2-10x
=-x2-x
=-(x2+x)
=3.