Answer:
C(p) Â = 4,96 (in thousands of dollars)
l = 2980 $ Â invest in labor
k = 2980 $ invest in equipment
Step-by-step explanation:
Information we have:
Monthly output  P = 450*l*k    ⇒  k = P/450*l
But the production need to be 4000
Then k = 4000/450*l
Cost of production = l * k   (in thousands of dollars)
C(l)  =  l  + 4000/450*l
Taking derivatives (both members of the equation)
C´(l) = 1 - 400 /45*l²      ⇒ C´(l) = 0      ⇒ 1 - 400/45l²  = 0
45*l² -  400  = 0        ⇒  l²  = 400/45
l = 2.98 (in thousands of dollars)
l = 2980 $ And
k = 400/45*l      ⇒  k 400/45*2.98
k = 2.98 Â (in thousands of dollars)
C(p) = l + k
C(p) Â = Â 2980 + 2980 Â
C(p) Â = 5960 $