x的四次方减4x的三次方加2x二次方加4x减3=x^4-4x^3+2x^2+4x-3=x^4-x^3-3x^3+3x^2-x^2+x+3x-3=(x^4-x^3)-(3x^3-3x^2)-(x^2-x)+(3x-3)=x^3(x-1)-3x^2(x-1)-x(x-1)+3(x-1)=(x-1)(x^3-3x^2-x+3)=(x-1)[(x^3-3x^2)-(x-3)]...