Question

What is "complete a square"--my math book said to complete a square, but does not teach how to or what it means. Math is not my strong point.

Answer 1

See if you can understand it here
http://en.wikipedia.org/wiki/Complete_the_square
or come back if something not clear

Answer 2

look at the Background and Basic Examples Sections...

Answer 3

I didn't really get it. I understood that the example wasn't a perfect square, but other than that, I'm lost...it didn't explain why they did what they did, or how they came up with it.

Answer 4

Using the example from the link:
x^2 + 10 x + 28 = 0 (lets put it equal to 0 for easy explanation)
Subtract 3 from both sides of this equation.

Answer 5

x^2 +10x + 28 -3 = -3, right?

Answer 6

in order to complite a squere follow this five steps
1)make sure that the coefitient of X^2 is +1
2)take the constant to the ather side
3)add half * coeficient of X and squere it both sides
4)take the terms with squeres on the left put them together seperated by the sign of the midle term and do nomarl simplification on the right
5) solve for X

Answer 7

estudier--why subtract three from both sides? Where do you come up with three? That's what's confusing me. Three seems completely arbitrary, so I'm not sure how to apply this to the problems in my math book.

Answer 8

I agree it looks like a trick, it is because we know that will turn the left hand side into a perfect square ie (x+5)^2 Do you see that?

I was using this as example so you will be able to more easily see how the general method works, so bear with me, OK.

Answer 9

Now, say we have x^2 + px as the first 2 terms then we know that

(x + p/2)^2 will give us those same first 2 terms, with me so far?