In applications of derivatives how to determine the formula which has to be max or min?
To find point at which a given function y=F(x) is maximum or minimum, first we differentiate the function. Then we find point where y' = 0.
Then check whether y" is greater than or less than zero. If it is greater than zero, then it is point of minima.
If it is less than zero then it is point of maxima. If it is zero then it is point of inflection.