Hello,

Can someone please explain to me how to solve this problem.

Complete the square x^2-8x

I keep looking over the explanation in my book and i just doesn't make sense to me.

Thanks :confused:

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- Oct 30th 2007, 06:39 PMB1GG13Complete the Square??
Hello,

Can someone please explain to me how to solve this problem.

Complete the square x^2-8x

I keep looking over the explanation in my book and i just doesn't make sense to me.

Thanks :confused: - Oct 30th 2007, 07:32 PMThePerfectHacker
x^2 - 8x = (x^2 - 8x + 16 )- 16 = (x-4)^2 - 16

- May 10th 2015, 02:09 PMTheVirtualMathematicianRe: Complete the Square??
https://www.youtube.com/watch?v=1BVxDi6W8sI

This video explains the process - May 10th 2015, 04:33 PMHallsofIvyRe: Complete the Square??
You should know that $\displaystyle (x- a)^2= x^2- 2ax+ a^2$. Comparing that to $\displaystyle x^2- 8x$ you can see that "2ax" must be "8x" so that 2a= 8, a= 4. And then $\displaystyle a^2= 4^2= 16$. To make $\displaystyle x^2- 8x$ into the "perfect square" $\displaystyle x^2- 8x+ 16$ we need to add 16- and, of course, in order not to change the value we must also subtract 16: $\displaystyle x^2- 8x+ 16- 16= (x- 4)^2- 16$.