y=-x^2 -8x -16
-x^2 tell yu its a parabola that open DOWN, axis vertikal
tu get zeors (x-intersepts) set y=0 or x^2 +8x +16=0
zeroes...x=-4 & x=-4
tu get the "vertex" get slope=differensheate...
dy/dx=-2x -8=0, or x=8/-2=-4
this tell yu the top av kerv is at x=-4 & y=0....(-4,0)
axis av prabola gotta go thru this point, so axis=x=-4
y-intersept: set x=0...y=-16