2x的三次方-3x的平方-10=?

X^2+X+3=0===>x是复数解
X^5+3X^4+2X^3+2X^2-10x
=x^5+x^4+3x^3+2x^4+2x^3+6x^2-3x^3-3x^2-9x-x^2-x-3+3
=x^3(X^2+X+3)+2x^2(X^2+X+3)-3x(X^2+X+3)-(X^2+X+3)+3
=3