The percent of concentration of a certain drug in the bloods…

The percent оf cоncentrаtiоn of а certаin drug in the bloodstream x hourse after the drug is administered is given by:  K(x)=2xx2+25   How many hours after the drug is administered does the concentration in the bloodstream reach  a maximum? Do not enter the units. Unless the answer is a whole number, round to the nearest tenth of an hr.