Y = x2 + 8x + 16 – 3 – 16
in vertex form

 y = (x+4)^2 -19

Step-by-step explanation:

y = x^2 + 8x + 16 – 3 – 16

You are almost done with completing the square

y = (x^2 + 8x + 16) – 19

  = (x+4)^2 -19

This is in vertex form  y= a(x-h)^2 +k  where (h,k) is the vertex

step-by-step :