Completing the Square HELP?

Ax^2+ Bx+C=0 is the standard form.....in order to complete the square you take the B divide it by 2 and then suare your answer which in this case would be 25...(10/2)^2....then what you do to one side you have to do to the other so you add 25 to both sides which gives you x^2+10x+25=128...then you factor the left side which gives you (x+5)^2=128....next you take the square root which gives you x+5= square root of 128 then you subtract 5 from both sides and you get x= 5+/- square root of 128.......do you get it?....i hope it was helpful and good luck on your hw!!