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How do I fucking complete a square?
I search for it everywhere and there is everytime a different way to do it, I just get so confused when I see there is an easier method I then wonder why that other person did it by adding/substracting b/2a (b^2)/4a
So how do I fucking go on this shit?
What's the definitive method of completing a square.
Khan academy tells me to simply search for the b coefficient but it sounds retarded.
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>>9130851
Consider that (a+b)^2 = a^2 + 2ab + b^2.
So if you have a quadratic expression in the form x^2 + 2bx + b^2, you know how to factor it easily. Now imagine you have a quadratic in the form x^2 + 2bx + c = 0. How can you get it into your factorable form? Simply subtract c from both sides, then add b^2 to both sides. That is, take half of the coefficient of x, square it, and add to both sides. Then you have (x+b)^2 = -c + b^2, so x + b = +- sqrt(b^2 - c).
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>>9130868
Also, if the coefficient of x^2 isn't 1, then just divide through by that coefficient first.
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ax^2+bx+c=0
x^2+(b/a)x=-(c/a)
x^2+(b/a)x+(b/2a)^2=(b/2a)^2-(c/a)
(x+(b/2a))^2=(b/2a)^2-(c/a)
Now you can find the zeros by taking the square root of both sides.
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>>9130891
Or you memorise this.
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