# revenue function

• Oct 17th 2009, 05:34 PM
samtheman17
revenue function
The rate of change of q with respect to time (in days) is dq/dt= 60 . The rate of change of revenue over time, dR/dt, is to be found when q= 480 . Differentiate both sides of the equation R= 120 q- q^2/240 with respect to t to get dR/dt= 120 dq/dt − 1/ 120 q dq/dt.

Now substitute the known values for q and dq/dt to get dR/dt= ___*___ - 1/ ___ * ___ * ___

Thus the revenue is increasing at the rate of \$_____ per day

i dont know how to sub in the answers to get the correct answer!
• Oct 17th 2009, 06:25 PM
rn443
Quote:

Originally Posted by samtheman17
The rate of change of q with respect to time (in days) is dq/dt= 60 . The rate of change of revenue over time, dR/dt, is to be found when q= 480 . Differentiate both sides of the equation R= 120 q- q^2/240 with respect to t to get dR/dt= 120 dq/dt − 1/ 120 q dq/dt.

Now substitute the known values for q and dq/dt to get dR/dt= ___*___ - 1/ ___ * ___ * ___

Thus the revenue is increasing at the rate of \$_____ per day

i dont know how to sub in the answers to get the correct answer!

dR/dt = 120q' - q'*q/120. Plug in q = 480 and q' = 60.