The price (in dollars)
p
and the quantity demanded
q
are related by the equation:p
2
+
2
q
2
=
1100
.
If
R
=
p
q
is revenue,
d
R
d
t
can be expressed by the following equation:
d
R
d
t
=
A
d
p
d
t
,
where
A
is a function of just
q
.