math
posted by Math .
The sales (in millions of dollars) of a laser disc recording of a hit movie t years from the date of release is given by
S(t)=[{4t+1}/{t^3+1}]
How fast is the sales changing one year the laser discs are released?

substitute t=1 in
S(t)=[{4t+1}/{t^3+1}]
to get
S(1)=[{4*1+1}/{1^3+1}]
Can you evaluate S(1)?