Answer:
Step-by-step explanation:
C'(x)=-40+0.08 x
C'(x)=0 gives
-40+0.08 x=0
x=40/0.08=500
C"(x)=0.08>0 at x=500
so C(x) is minimum if x=500
so 500 cars need to be produced for minimum cost.
or we can solve by completing the squares.
c(x)=12000+0.04(x²-1000 x+250000-250000)
=12000+0.04(x-500)²-0.04×250000
=0.04 (x-500)²+12000-10000
=0.04(x-500)²+2000
c(x) is minimum if x=500