$x^2+2kx+k+6=0$ 

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$y=x^2+2kx+k+6$

→ $y=(x+k)^2-k^2+k+6$

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判別式

${\rm D}=4k^2-4×1×(k+6)$

$\quad=$24>0

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軸

$x=-k$

$\ =$3>0

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$y$軸との交点

$y=k+6$

$\ =$3>0

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直線$x=1$との交点

$y=$

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直線$x=2$との交点

$y=$

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刻み　1

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x² +

kx +

k +

=0