若多项式2x^3+mx^2-7x+n中有因式(x-1)(x+2)求m,n的值

设另一个因式是A则2x³+mx²-7x+n=A(x-1)(x+2)x=1时,x-1=0所以右边A(x-1)(x+2)=0所以左边也等于0即x=1,2x³+mx²-7x+n=2+m-7+n=0m+n=5 (1)同理,x=-2,x+2=0,右边等于0所以x=-2,2x³+mx²-7x+...