# Thread: Completing the square annoying problem

1. ## Completing the square annoying problem

So I wrote a test last Friday and the question was to complete the square which I know how to do but they gave me this crazy equation
5x2 = -x

5x2 + x = 0

(x2 + x + x/5/2) - x/5/2 = 0

(x2 + x/5 + x/5/2) = x/5/2

this is where I got stuck

2. ## Re: Completing the square annoying problem

Originally Posted by fanna1119
So I wrote a test last Friday and the question was to complete the square which I know how to do but they gave me this crazy equation
5x2 = -x

See if you can follow this:
$5\left(x^2+\frac{1}{5}x+\frac{1}{100}\right)-\frac{1}{20}$

3. ## Re: Completing the square annoying problem

I see what I should be doing but I fail to get the grip of the equation.

seeing that you factorized the 5x^2 then 5(x^2 + 1/5x + 1/100) -1/20

which I am not getting in this case since I usually workout the three term factoring using the quadratic formula which didn't workout
because of the x confusing me.

hope you understand what I mean by this
thanks!

4. ## Re: Completing the square annoying problem

Originally Posted by fanna1119
I see what I should be doing but I fail to get the grip of the equation.
seeing that you factorized the 5x^2 then 5(x^2 + 1/5x + 1/100) -1/20 which I am not getting in this case since I usually workout the three term factoring using the quadratic formula which didn't workout hope you understand what I mean by this.
No I actually have no idea what you mean. I fail to see how the quadratic formula has anything to do with it.

5. ## Re: Completing the square annoying problem

Originally Posted by fanna1119
I see what I should be doing but I fail to get the grip of the equation.

seeing that you factorized the 5x^2 then 5(x^2 + 1/5x + 1/100) -1/20

which I am not getting in this case since I usually workout the three term factoring using the quadratic formula which didn't workout
because of the x confusing me.

hope you understand what I mean by this
thanks!
It is difficult o understand what you mean. I agree with @Plato that the quadratic formula has no purpose here (although the quadratic formula is derived by completing the square, which is besides the point). The quadratic formula will not help you here. You have to be more clear when you state that the x is confusing you. Which x? The one in the original equation? Are confused about where the 1/5 in the factored polynomial came from? Please state your question clearly and unambiguously so we can help you properly.