Hello Ash Ash, Perhaps I misunderstand your question. I am assuming that you are no longer interested in a maxima.

To find the value of an expression for a particular value of a parameter, you can use slash-dot with a rule:

 expr = a Cos[ b x]

 expr /. a -> 2

 expr /. {a -> 2, x -> 3}

 expr /. {a -> 2, b -> 3, x -> Pi}

More information can be found here: tutorial/ApplyingTransformationRules

Hello Ash Ash,

I am sorry if my response appeared to be rude to you. It was not my intention. Danny is correct that the probability of getting a response is increased if code can be cut-and-pasted from the post.

I believe that basic questions should be encouraged. However, if the poster makes an effort (to fix syntax, look for a working example in the documentation, and make sure that all variables which be defined are defined), that effort will be rewarded by learning.

I pasted the picture, only to show what i really want to ask. in this case the syntax to be used..

3) is there even a rule that i cannot ask basic or easy questions in this forum?? in that case, it is a pity for beginners .

Hello, While at risk of encouraging those who do not read the posting guidelines or the documentation....

Pn = 40;
\[Mu]p = 0.2;
cp = -Pn (
  0.066 (56250.` \[Delta]^2 + 24496.` \[Delta] \[Mu]m - 
     18723.` \[Delta]^2 \[Mu]m - 480.` \[Mu]m^2 + 
     540.` \[Delta] \[Mu]m^2 - 
     135.` \[Delta]^2 \[Mu]m^2))/(\[Delta] (168.` \[Delta] - 
     9.` \[Delta]^2 + 160.` \[Mu]m - 180.` \[Delta] \[Mu]m + 
     45.` \[Delta]^2 \[Mu]m)) (\[Delta] - 1)/\[Mu]p
temp = cp /. \[Mu]m -> 1
Plot[temp, {\[Delta], 0, 1}]
FindMaximum[temp, \[Delta]]

with hopes that I can get someone to look at my CUDA questions on community.... sigh. WCC

actually no output displays..

Find derivative

D[Cp[\[Delta]], \[Delta]]

Then solve

Solve[D[Cp[[Delta]], [Delta]]==0, [Delta]]

This will give value of delta at maximum.