Answer: $35 is the selling price and $1225 is the maximum revenue.
Step-by-step explanation:
Since we have given that
[tex]R(x)=-x^2+70x[/tex]
We need to find the maximum revenue.
So, We will first derivative it w.r.t. x.
So, it becomes,
[tex]R'(x)=-2x+70[/tex]
Now, we will find critical points.
So, R'(x) = 0
So, it becomes,
[tex]-2x+70=0\\\\-2x=-70\\\\x=\dfrac{70}{2}=35[/tex]
Now, to check whether it yields maximum revenue or not.
So, second derivative w.r.t. x, we get that
R''(x) = -2<0
So, At $35, it yields maximum revenue.
Amount of maximum revenue would be
[tex]R(35)=-(35)^2+70\times 35=-1225+2450=\$1225[/tex]
Hence, $35 is the selling price and $1225 is the maximum revenue.