Final answer:
The cost as a function of price, given the demand function x=9000-30p and the cost equation c=90000+30x is c(p) = 360000 - 900p after substituting x from the demand function into the cost equation and simplifying.
Step-by-step explanation:
To find the cost as a function of price given the demand function x=9000-30p and the cost equation c=90000+30x, we first need to express x in terms of p and then substitute this expression into the cost equation.
The demand function already gives us x in terms of p. Substituting x from the demand function into the cost equation, we get:
c = 90000 + 30(9000 - 30p)
Simplifying this, we have:
c = 90000 + 270000 - 900p
Therefore, the cost as a function of price is:
c(p) = 360000 - 900p