Hi guys basically I have got a bit of a problem with completing the square...

If I had to complete the square of x^{2}-14x+36=0

I would form the square of (x-7)^{2}

I would then expand the brackets to get x^{2}-14x+49

I would then combine this with the original equation to get x^{2}-14x+49+36=0

I then tidy it up to get x^{2}-14x+85=0

I then take 85 from both sides to leave me with x^{2}-14x=-85

My reaction to that would be to try and remove the^{2}by square rooting each side but then I would be rooting a negative? Can someone give me some help by talking me through what to do as opposed to just showing me a page of maths? Sorry but I just don't learn particularly well that way.

Thanks in advance for anyone who helps me, it is appreciated.