Question 1169985
this is a quadratic equation.
replace n with x to get:
c(x) = 1.2x^2 - 24x + 690
this is in standard form where:
a = coefficient of x^2 term = 1.2
b = coefficient of x term = -24
c = constant term = 690
the minimum point of this equation will be when x = -b/(2a)
that becomes when x = -(-24)/(2*1.2) = 24/2.4 = 10
when x = 10, 1.2x^2 - 24x + 690 = 1.2*10^2 - 24*10 + 690 = 570.
the minimum point of the equation will be at the point (x,y) = (10,570).


here's the graph.


<img src = "http://theo.x10hosting.com/2020/111804.jpg" >