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Math Help - Complete the Square??

  1. #1
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    Question Complete 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
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  2. #2
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    x^2 - 8x = (x^2 - 8x + 16 )- 16 = (x-4)^2 - 16
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  3. #3
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    Re: Complete the Square??



    This video explains the process
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  4. #4
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    Re: Complete the Square??

    You should know that (x- a)^2= x^2- 2ax+ a^2. Comparing that to x^2- 8x you can see that "2ax" must be "8x" so that 2a= 8, a= 4. And then a^2= 4^2= 16. To make x^2- 8x into the "perfect square" x^2- 8x+ 16 we need to add 16- and, of course, in order not to change the value we must also subtract 16: x^2- 8x+ 16- 16= (x- 4)^2- 16.
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