I'm not sure how to solve this with fixed startup cost component 

If the marginal cost of producing x widgets is $C'(x)=25-0.5x+0.002x^2$
(measured in cents per widget) and the fixed start-up cost for the business is 
$C(0)=\$30,000$

1. find the total cost of producing the first $500$ widgets,
2. find the cost of producing the next $500$ widgets.

I'm not sure how to solve this with fixed startup cost component 

If the marginal cost of producing x widgets is $C'(x)=25-0.5x+0.002x^2$
(measured in cents per widget) and the fixed start-up cost for the business is 
$C(0)=\$30,000$

1. find the total cost of producing the first $500$ widgets,
2. find the cost of producing the next $500$ widgets.

I have found the cost function as C= 25x - 0.25x^2 +0.00067...x^3 + A

C(500) = 25(500)-0.25(500)+0.002/2(500)^3+$30,000= 31,373.75

C(1000) = 25(1000)-0.25(1000)+0.002/2(1000)^3+$30,000= $40,247.50

C(1000) - C(500) = $40,247.5 - 31,373.75 = 8873.75

Cost of first 500 = $31.373.75

Cost of next 500 = $8873.75

I'm not sure if I have this right.