complete teh square
isolate x terms
y=(x^2+6x)-12
take 1/2 of 6 and squaer it then add positive and negative inside parenthasees
6/2=3, 3^2-9
y=(x^2+6x+9-9)-12
comlete the square
y=((x+3)^2-9)-12
y=(x+3)^2-9-12
y=(x+3)^2-21
for
y=(x-h)^2+k
vertex is (h,k)
axis of symmetry is x=h
given
y=(x-(-3))^2+(-21)
vertex is (-3,-21)
axis of symmetry is x=-3
