Answer:
-(x+1)²+4
Explanation:
y = -x²-2x-3
= -[x²+2x+3]
= -[(x²+2x)+3]
{formulae to get the vertex form is add (b/2)² to the expression
(2/2)² = 1}
= -[(x²+2x+1)-1+3]
{we are adding so we have to subtract the same number as well}
= -[(x²+2x+1)+2]
thus vertex form,
y = -(x+1)²+2