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# Completing the square watch

f(x)=x^2 -6kx + 4,
K is a positive constant.

Express f(x) in the form (x-a)^2 + b, giving the values of a and b in terms of K.

I'm just not sure what to do. I've tried a few times. This should probably be simple, and I'm usually alright with this, but the K is throwing me off.
2. x^2 - 6kx + 4 = (x - 3k)^2 - 9k^2 + 4

so a=3k and b = -9k^2 + 4

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Updated: October 10, 2009
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