DS [Algebra]

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?
(A) d = 3
(B) b = 6

Solution:

Resolving the equation produces
bx +c = 2dx + d^2 for all values of x.

Point to remember:

Here we can equate co-efficient of x and constants.
i.e. b = 2dx and c = d^2

Now the question is pretty easy to solve, and both the statements alone are sufficient to deduce the correct answer.