N.b., this is copied from an answer I wrote for someone else.Thinking about the graph of y, the rate of change is zero whenever there is an extremum.
First, differentiate y.

Next, find the zeros of y' by factoring.

Now, we substitute these x-values into the
original equation to find the coordinates.
Step-by-step explanation:
D=9
A=pie*radius^2
=3.14*9/2*9/2
=63.58
=64
Step-by-step explanation:

The product of
is negative whereas the product of 
Answer:
the first one
Step-by-step explanation: