In the solution to problem 1.1.11, there's is one line in the solution that is giving me trouble. Here is the problem:
is a twice differentiable real function such that
. Find all real numbers
at which the area between the graph
, the tangent to the graph at
, and the lines
attains its minimum value.
At some point we need to differentiate (with respect to c)
but I'm getting other things which don't allow successful solution to the problem (my expression for
doesn't have a
Can someone explain?