已知x^2-1=3x,则多项式3x^3-11x^2+3x+2的值为0

问题描述:

已知x^2-1=3x,则多项式3x^3-11x^2+3x+2的值为
0

∵x^2-1=3x,
那么x^2-3x=1

3x^3-11x^2+3x+2
=3x^2-9x^2-2x^2+3x+2
=3x(x^2-3x)-2x^2+3x+2
=3x-2x^2+3x+2
=-2x^2+6x+2
=-2(x^2-3x)+2
=-2*1+2
=0