Question 48689
the differential gives you a turning point on a curve, either a max or a min (or a point of inflexion).


p(x)= -0.2x^2+300x-200 
p'(x)= -0.4x+300 where p'(x) is the differential
p'(x)= -0.4x+300 = 0
0.4x = 300
x = 300/0.4
x = 750


p''(x) = -0.4 which is NEGATIVE. This is therefore a MAXIMUM point.


So profit is maximised at x=750


jon.