SOLUTION: Can someone please explain how i work this out? im finding it very difficult to understand. The size of a colony of rare termites is related to the size of the colony’s mound. Th

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Can someone please explain how i work this out? im finding it very difficult to understand. The size of a colony of rare termites is related to the size of the colony’s mound. Th      Log On


   



Question 965766: Can someone please explain how i work this out? im finding it very difficult to understand.
The size of a colony of rare termites is related to the size of the colony’s
mound. The relationship can be modeled using the equation below:
ℎ = −N^2 + 25N − 5
Where N is thousands of termites and ℎ is the height of the mound in
centimeters.
Sketch the graph showing the relationship between the number of termites(x-axis)and the height of the mound (y-axis).Show the coordinates of the y-intercept only.

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
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%28N-r%29%5E2, 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%5E2%2B25N-5=0;
N=%28-25%2B-+sqrt%2825%5E2-4%2A%28-1%29%28-5%29%29%29%2F%282%2A%28-1%29%29
%28-25%2B-+sqrt%2825%5E2-20%29%29%2F%28-2%29
%2825%2B-+sqrt%28605%29%29%2F2
highlight_green%28N=%2825%2B-+11%2Asqrt%285%29%29%2F2%29, the roots or x-intercepts.

Find the h intercept when N=0.
highlight_green%28h=-5%29, the point (0,-5).


graph%28300%2C300%2C0%2C50%2C0%2C170%2C-x%5E2%2B25x-5%29
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