Question 877935
Try a parabola.
{{{y=a(x+1)(x+7)}}}, accounts for the roots.


Notice that -4 is in the middle of -1 and -7.  Notice that y=7 is greater than the x-axis.  The parabola's vertex is a maximum, and {{{a<0}}}.


Solve symbolically for a.
{{{a=y/((x+1)(x+7))}}}
Use coordinates of vertex.
{{{a=7/((-4+1)(-4+7))}}}
{{{a=7/(-3*3)}}}
{{{a=-7/9}}}


Equation:  {{{highlight(y=-(7/9)(x+1)(x+7))}}}