Question 337182
No, the function is already in vertex form.
{{{a=-10/3}}}
{{{h=-5}}}
{{{k=-5}}} 
The min or max value occurs at the vertex. 
Since the coefficient of the {{{x^2}}} term is negative, the parabola opens downwards and the max value is 
{{{ymax=k=-5}}}
.
.
.
{{{drawing(300,300,-10,10,-15,5,circle(-5,-5,0.3),grid(1),blue(line(-5,20,-5,-20)),graph(300,300,-10,10,-15,5,-(10/3)(x+5)^2-5))}}}