提示:构造因式2+x
x²+kx+6
=x²+2x+(k-2)x+6
=x(x+2)+(k-2)x +2(k-2)+6-2(k-2)
=x(x+2)+(k-2)(x+2)+(10-2k)
要x²+kx+6能被2+x整除,常数项10-2k=0
k=5