x的4次方-3x的3次方-2x的平方+5x+3
=x^3(x-1)-2x^3-2x^2+5x+3
=x^3(x-1)-2x^2(x-1)-4x^2+5x+3
=x^3(x-1)-2x^2(x-1)-4x(x-1)+x+3
=x^3(x-1)-2x^2(x-1)-4x(x-1)+(x-1)+4
=(x^3-2x^2-4x+1)(x-1)+4
商式:x^3-2x^2-4x+1
余式:4