Suppose that a company's profit function over time is
p(x)=? 0.4x^3+5x^2+10 thousand dollars, where x is the number of years since the end of 2010. so, for example, x=2 corresponds to the end of 2012, and x=2.1 corresponds to the beginning of 2013.)
the point of diminishing returns is x= 4.17 (give your answer as a fraction or as a decimal with at least 3 decimal places.)
this corresponds to the year ?
i could find the point of diminishing returs, but i can not find this corresponds to the year.
how can i solve?