a)
m = Δy / Δx = (192 - 304) / (15 - 1) = - 8
p(x) = - 8·(x - 1) + 304 = 312 - 8·x
p(25) = 112 GE
b)
E(x) = x·p(x) = 312·x - 8·x^2
E(1) = 304
E(15) = 2880
E(25) = 2800
c)
G(x) = E(x) - K(x) = (312·x - 8·x^2) - (x^3 - 26·x^2 + 273·x + 380) = - x^3 + 18·x^2 + 39·x - 380
d)
G'(x) = - 3·x^2 + 36·x + 39 = 0 --> x = 13 ME
p(13) = 208
G(13) = 972
e)
G(x) = - x^3 + 18·x^2 + 39·x - 380 = 0 --> x = 4 bis x = 19