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anonymous

  • 5 years ago

How do you complete a square for example: y=x^2-6x+4

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  1. nowhereman
    • 5 years ago
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    Find the numbers a and b so that the x^2 and x part of (ax + b)^2 and your polynomial are the same. Then add the difference in the part without x, to get equality.

  2. anonymous
    • 5 years ago
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    you lost me

  3. anonymous
    • 5 years ago
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    so is a 1 b 6?

  4. amistre64
    • 5 years ago
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    when you "complete the square", you end up with: -b/2a +- sqrt(b^2 -4ac)/2a completeing the square is just the proof of the quadratic formula

  5. anonymous
    • 5 years ago
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    Ok so no calc expierence just algebra

  6. amistre64
    • 5 years ago
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    in your example: a = 1 , b=-6 , c=4

  7. amistre64
    • 5 years ago
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    just algebra :)

  8. anonymous
    • 5 years ago
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    in order to get the answer do I do the wuadratic formula?

  9. amistre64
    • 5 years ago
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    When we square a value for "x", we get a quadratic equation; the name quadratic is a fancy latin word meaning: we squared it and got a result.

  10. amistre64
    • 5 years ago
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    yes, in order to get your answers for "x" you can use the quadratic formula..

  11. amistre64
    • 5 years ago
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    (x+3)^2 = x^2 +6x +9 right? but if we have the equation: x^2 + 6x +6 we need to convert it to a "complete" square so that we can factor it.....

  12. amistre64
    • 5 years ago
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    in fact, we just need to add 9 and subtract 9 to the equation to make it still equal the same amuont right? +9-9 = 0 and 0 added to any number doesnt change the value.

  13. anonymous
    • 5 years ago
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    hold on ok so I just got the answer for x thru the quadratic formula now what do I do?

  14. radar
    • 5 years ago
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    \[x ^{2}-6x+4=y\] Take half of the coefficient of x, in this case half of the -6 giving you a -3. Square this and add it your equation\[x ^{2}-6x +(-3)^{2}+4=y +(-3)^{2}\] \[x ^{2}-6x+9 =y-4-9=y-13\] \[(x-3)^{2}=y-13\]\[x-3=\pm \sqrt{y-13}\]

  15. amistre64
    • 5 years ago
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    x^2 + 6x +6 x^2 +6x +9 -9 +6 (x^2 +6x +9) -3 ^^^^^^^^^ this part here is now a "completed square" (x+3)^2 - 3

  16. amistre64
    • 5 years ago
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    if you used the quadratic formula to get the answer,,,then thats your answer :)

  17. radar
    • 5 years ago
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    \[x=3\pm \sqrt{y-13}\]

  18. amistre64
    • 5 years ago
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    radar did a fine job at that...great job :)

  19. radar
    • 5 years ago
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    Time I finished typing it was answered LOL

  20. amistre64
    • 5 years ago
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    lol....at least its there for the rest of posterity to read ;)

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