if is a cost function. Find the average cost function. At what level of production q, is there a minimum average cost?

how do i calculate this? I have got no idea

The "average value" of a continuous function, between x= a and x= b, is given by $\frac{\int_a^b f(t)dt}{b- a}$. To find the average cost, use "x" rather than b as upper bound: $\frac{\int_a^x f(t)dt}{x- a}$. Of course, to find the max or min of a function you set the derivative equal to 0.