#20

When finding max and/or min for the remainder of the course, you should show solving derivative = 0, not "maximum" from graph.  (In a very technically detailed or complicated function, may use Wolfram Alpha, TI-89, or equivalent, to solve an equation, or even d( ) to differentiate, if you LABEL that is what you did.)  Of course, assignments and problems may occasionally instruct otherwise.
Read 6.1.
6.1; 1, 7, 28, 47, 50+use 2nd deriv test, assuming all constants are positive,
On 47: Graph only M, not derivatives. Hint: You can use quadratic formula to find the solution.
6.1; 51&52&53 done together.
6.2; 9.