if for all x, x^2 + ax + b = (x+c)^2, then a = ?

(1) b = 0

(2) c = -3

The answer given in feifei is B, but I think it should be D, i.e. each is sufficient.

from (1), we know that c^2=b=0, c=0, so a=2b=0;

from (2), we know that a=2b= -6.

Where is wrong in my above reasoning?

Thanks a lot.

o, I see.

Thanks.

But in the pdf file I downloaded here, it's "b=0". Then it should

be corrected to be "b=9".