已知x的平方+ax+b乘以x+2得到的积是x的三次方+2x+12,求

(x^2+ax+b)*(x+2)
=x^3+ax^2+bx+2x^2+2ax+2b
=x^3+(a+2)x^2+(b+2a)x+2b=x^3+2x+12
则 a+2=0 b+2a=2 2b=12
a=-2 b=6 b=6