Question 1122915
s=9t, where t=seconds, and units are cm.
A=s^2
A=81t^2


at 1 second, 81 cm^2
2--324 cm^2
3--729 cm^2
4--1296 cm^2
f(t)=[9^2(t+1)^2-t^2]
This is f(t)=81 (2t+1)
so at 3 seconds  4 seconds will be 81(7) or 567 cm^2, 1296-729.