# Thread: AHHHH help! completing the square

1. ## AHHHH help! completing the square

So I have a problem that I cannot figure out for crap. Please walk through by COMPLETING THE SQUARE and getting what x equals.
4n^2+12+5=0
I know its (2n+1)(2n+5) but I need to know how to do it by completing the square so my first thing was 4n^2+12+36=31.

2. ## Re: AHHHH help! completing the square

4n^2 + 12 n + 5 = 0
it is always better to make coefficient of square term as 1. So divide the equation by 4, we get
n^2 + 3n + 5/4 = 0
n^2 + 3n = - 5/4
Add square of half the coefficient of n ( in this case ( 3/2)^2= 9/4 ) on both sides
n^2 + 3n + ( 3/2 )^2= 9/4 - 5/4
[n + 3/2]^2 = 1 that gives n + 3/2 = 1 or -1 that gives n = -1/2 OR -5/2

3. ## Re: AHHHH help! completing the square

Wow thanks haha