问一题:若x2+x+3=0 ,求代数式x5+3x4+2x3+2x2-10x的值

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问一题:若x2+x+3=0 ,求代数式x5+3x4+2x3+2x2-10x的值
问一题:若x2+x+3=0 ,求代数式x5+3x4+2x3+2x2-10x的值

问一题:若x2+x+3=0 ,求代数式x5+3x4+2x3+2x2-10x的值
x2+x+3=0
=>x^2+x+3=(x+1/2)^2+11/4>0
所以等式本身不成立
x5+3x4+2x3+2x2-10x
=(x^5+x^4+3x^3)+(2x^4+2x^3+6x^2)-(3x^3-4x^2+10x)
=x^3(x+x+3)+2x^2(x+x+3)-(3x^3-4x^2+10x)
=-3x^3+4x^2-10x
=(-3x^3-3x^2-9x)+7x^2-x
=7x^2-x
=7(-x-3)-x
=-8x-21