4.
E= Erlös, K= Kosten, G= Gewinn, x= Menge, p= Preis
K(x)= 50x+30000, E(x) = p(x)*x
G(x) = E(x)-K(x) = p(x)*x- K(x)
p(x) ermitteln: p(x) = mx+b
p(400) =120
p(220) = 138
m= (138-120)/(220-400)= 18/180 = -0,1
einsetzen:
120= -0,1*400+b
b=160
p(x) = -0,1x+160
G(x) = -0,1x^2+160x-(50x+30000) = -0,1x^2+110x-30000
G maximieren: G'(x) = 0
-0,2x-110 = 0
x= 550