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euclid2 · #3 December 3rd, 2008, 04:16 PM

Quote:

Originally Posted by skeeter

if $r_1$ and $r_2$ are two roots of a quadratic ...

$f(x) = k(x - r_1)(x - r_2)$

$f(x) = k[x^2 -(r_1 + r_2)x + r_1 \cdot r_2]$

now, substitute $r_1 = 2-\sqrt{3}$ and $r_2 = 2 + \sqrt{3}$ to determine the basic quadratic in [...], then use the fact that $f(1) = -2$ to find $k$

I'm not sure exactly what you mean, can you please work it down further? I have never learned this formula.