Need calculus BC help. (in Contests)

I will pay CBD per problem for your help in solving some calculus BC problems. If this belongs in FS/WTB i'll pay the fee but it wasn't CB related so I felt contests was sufficient. I will post one problem until it is finished then I will post the next. first:
For the function f(x)= (1/20)x^(2/3) -x, find the local maximums and minimums and inflection points.
I know that max's and min's means the derivative is 0 and for i.p.'s the second derivative is 0, but my numbers are not giving me an answer.

50k for this problem

I hope you mean you want to know how to do this, not just the answers. Otherwise I wouldn't feel comfortable.

CB has had a long standing unspoken policy (IIRC, it's been awhile) that we do not pay other players to do our homework. Just so you know. I'm not accusing you of this, just be careful.

oh really? then I apologize disregard the thread

does this mean i can still ask for help though w/o having to pay?

Like I said, I'll help if you don't understand, I'm just not going to do your homework for you, you know what I mean?

Why don't you show us your step-by-step and we will show you where/how you went wrong.

"I know that max's and min's means the derivative is 0 and for i.p.'s the second derivative is 0, but my numbers are not giving me an answer. "

You've taken the first and second derivative and set them equal to zero?

How are your numbers not giving you an answer?

okay so I got f'(x) = (1/30)x^(-1/3) -1 as the derivative. set that equal to 0 and solved for x and got x=1/27000. but on my graphing calculator the point 1/27000 is zero but its impossible to see what goes on on the graph

and then on the graph of f(x) the point 1/27000 has no significance it seems. again the graph is very hard to analyze and im not sure what to do

nevermind i solved this problem after a long battle with my calculator. Theres more but I guess I'll just shoot em my self