Question 965766
You can put the equation into standard form to help with graphing, and you can find the h intercept, and the x intercepts.


Standard form would be like, {{{h-k=a(N-r)^2}}}, with variables h for your function name, N for your independant variable name, "a" a factor, and vertex  (r,k).  Your function has the vertex as a maximum point.  You need to review how to Complete The Square.  See the lesson in my profile.


You can find the x-intercepts with  {{{-N^2+25N-5=0}}};
{{{N=(-25+- sqrt(25^2-4*(-1)(-5)))/(2*(-1))}}}
{{{(-25+- sqrt(25^2-20))/(-2)}}}
{{{(25+- sqrt(605))/2}}}
{{{highlight_green(N=(25+- 11*sqrt(5))/2)}}}, the roots or x-intercepts.


Find the h intercept when N=0.
{{{highlight_green(h=-5)}}}, the point  (0,-5).



{{{graph(300,300,0,50,0,170,-x^2+25x-5)}}}
Each mark on the vertical scale is 17, for thousands of centimeters of mound height.  Each mark horizontally is whole number thousands of termites.


The vertex is very near N=2.5