关于x 的多项式

rushcynthia

16.关于x 的多项式，x^2+6x+p ,p is constant, the value of p is?
a.x^2+6x+p=(x+r)^2对于所有的x和部分的r满足 b.x^2+6x+p=(x+m)(x+n) 选a

In robert's summary,the answer should be D.which is the right?I cannot work out the second equation using my poor math knowledge .

猫猫头

B中把没有X的部分统统加起来就是P了

isenetlab12

No, I don't agree with robert's answer.
condition(2) cannot give the answer
m=2,n=4,m=1, n=5,m=n=3, all can meet the equation, but p is different (8,5,9)
condition (1) can, since only r =3 can meet the equation.
Agree?

rushcynthia

x^2+6x+q=(x+m)(x+n)=x^2+(m+n)x+mn
没有x的项?refer to mn?but mn does not have specific value,how to determin q?

猫猫头

如果M和N是未知数的话，答案就是A