Velocity of blood according to a law discovered by the

Question

Question: VELOCITY OF BLOOD According to a law discovered by the 19th-century physician Jean Louis Marie Poiseuille, the velocity (in centimeters/second) of blood r cm from the central axis of an artery is given by

√(r) = k(R² - r²)

Where k is a constant and R is the radius of the artery . Show that the velocity of blood is greatest along the central axis.