# find values of A and B

• May 4th 2011, 08:08 AM
andyboy179
find values of A and B
hi,
i need to find the values of A and B to this question:

given that x^2 +12x +A ≡ (x+B)^2

Find values of A and B.

im unsure what to do because before i did:
(x+6) (x+6)
= x^2+12+36

A=36 B=6

however it was wrong so i need to know where i am going wrong and how i get it correct!

help would be great!

thanks!
• May 4th 2011, 08:17 AM
Quacky
You have the correct solution, are you sure this is the exact wording/equation?
• May 4th 2011, 08:21 AM
Plato
Quote:

Originally Posted by andyboy179
given that x^2 +12x +A ≡ (x+B)^2
Find values of A and B.
A=36 B=6
however it was wrong

Are you given a proposed answer?
• May 4th 2011, 08:22 AM
andyboy179
yes! my teacher wrote in my book "How?" "did you understand it?" "ask me"

but i can't see how im wrong because im sure its correct, that why i asked here so i could know where im going wrong!
• May 4th 2011, 08:22 AM
andyboy179
Quote:

Originally Posted by Plato
Are you given a proposed answer?

my book had been marked, see above post to she what she wrote!
• May 4th 2011, 08:31 AM
Quacky
Quote:

Originally Posted by andyboy179
yes! my teacher wrote in my book "How?" "did you understand it?" "ask me"

but i can't see how im wrong because im sure its correct, that why i asked here so i could know where im going wrong!

Quote:

Originally Posted by andyboy179
my book had been marked, see above post to she what she wrote!

She isn't saying that you're wrong. She is saying that your method is concerning because it looks like you've randomly guessed.

Start the problem from scratch and try to solve it this way: expand the brackets on the right hand side, and then equate the coefficients.
• May 4th 2011, 08:33 AM
andyboy179
i know what to do now, thanks for clearing that up!!
• May 4th 2011, 09:11 AM
topsquark
Quote:

Originally Posted by andyboy179
hi,
i need to find the values of A and B to this question:

given that x^2 +12x +A ≡ (x+B)^2

Find values of A and B.

It's a little late, but I would propose an altered problem statement:
Quote:

Given that x^2 +12x +A = (x+B)^2 is satisfied for all x find values of A and B.
Otherwise this problem has an infinite number of solutions for A and B.

-Dan