Check my work? The equations given were R(x)=-x^2+400x and C(x)=x^2+40x+100. We were asked to find the maximum profit and minimum average cost. (I'm having trouble remembering how to find a minimum and maximum, so please help with that, if you can!)

Question

For Max Profit, I got $16,100.
For Min Avg. Cost, I got $20, which feels really wrong.

Help?

Answer 1

P(x) = R(x)-C(x) = -2x^2+360x-100
P'(x) = -4x+360
P'=0 at x=90
P(90)=16100
good work

AvgCost
A(x) = C(x)/x = x+40+100/x
A'(x) = 1-100/x^2
A'=0 at x=10
A(10) = 60

Answer 2

Ohhhh. I see what I did wrong in that second one!
Thanks for all your help!(: