Thanks

ComplexExpand[(1 + I)^n + (1 - I)^n]=2^(1 + n/2) Cos[(n \[Pi])/4]

[1      1        1         1        1      x - I y]
             [- = -------, ------- = -------, ------- = -------]
             [z   x + I y  x + I y   x + I y  x + I y    2    2]
             [                                          x  + y ]
the expression seems interestion,hehe

the shourtcut keys-Ctrl+space seems no response,so how to use the fuction "Command Completion"?

really detailed,Let me have a good learning,thanks,

really detailed,Let me have a good learning,thanks,

so concise,I like it ,thanks,

so concise,I like it ,thanks,