## Precalculus (6th Edition) Blitzer

$y=-6x-9$
$m=f^{,}(x)=\dfrac{d^2x}{dx^2}=2x$ Put $x=-3$ So, $m=f^{,}(-3)=2(-3)=-6$ The equation of the line is: $y=mx+c \implies c= y-x$ Now, $y=9-(-6)(-3)=-9$ So, $y=-6x-9$