天山 7－5

lingdang1988

Q5，

If b, c and d are constants and x^2+bx+c=(x+d)^2 for all values of x, what is the value of c?

(1) d=3

(2) b=6

答案是D 我的是E

（1）（2）各自是算不出来c的呀？即便加起来，x这个变量也不知道，怎么得出D答案的？

periodic

if it's for all values of x,

then

c = d^2
b = 2d

from either 1 or 2, you can work out the value of c.

lingdang1988

THANKS !!!I  SEE!!