math
posted by Sasha .
a spherical balloon with radius r inches has volume V9r) =(4/3)πr^3. Find a function that represents the amount of air required to inflate the balloon from a radius of r inches to a radius of r+1 inches

Additional volume of air required
=f(r+1)f(r)
=(4/3)π(r+1)³  (4/3)πr³
= ...