when dividing by x-1 x+2 x-2 x-3 the polynomial p(x)=x^4+ax^3+bx^2+c+d remainder 0
Do you mean p(x)=x^4+ax^3+bx^2+cx+d ???
(x-1)*( x+2)*( x-2)*( x-3)=x4-4x3-1x2+16x-12
a=-4 b=-1 c=16 d=-12