x/root x+25 x in years find total change in population from year 0 to 39

Question

The population of a city is expected to grow at the rate of 

x/

x + 25

 thousand people per year after x years. Find the total change in population from year 0 to year 39.

Answer 1

Let P(x)=x/√(x+25), P(0)=0, P(39)=39/√64=39/8, so the change is 39/8 thousands or 4875.