The profit obtained when x barbecues are sold is

P(x) = 100 x − 3x^2 (lnx) dollars . Find the marginal profit when 4 are sold.

2 answers

P(4) =
100(4) - 3(16)ln(4)
= ..

I assume you have a calculator to get appr 333.46
the marginal profit is

dP/dx = 100 - 6x lnx - 3x

so, now plug in x=4