Question 1183810
{{{y= -x^2-3}}}


the vertex form of a quadratic equation is
 
{{{y=a(x-h)^2+k }}}....where {{{h}}} and {{{k}}} are coordinates of vertex


If {{{a<0 }}}, the parabola opens {{{downward}}}. In this case the vertex is the {{{maximum}}}, or highest point, of the parabola. 

you have

{{{y= -1*(x-0)^2-3}}}=>the parabola opens {{{downward}}}, {{{h=0}}} and {{{k=-3}}}=> vertex is at ({{{0}}}, {{{-3}}})


{{{ graph( 600, 600, -10, 10, -10, 10, -x^2-3) }}}