I wonder how to solve symbolically for like following coupled ODEs in Maple? 

On the other hand, I want to write the code for step by step solution of this problem. But I didn't find algorithm of the solution on the some books. Do you know some books including solving coupled ODEs ?

I don' t understand what do these notations stand for? I know that there are some notations like these in Maple. How can I find meanings of the all of them?

restart:
tf:=2:
n:=2:
X[1]:=t->t^2:
A[1]:=diff(X[1](t),t,t):
plot(A[1](t),t=0..tf,labels=["Time t","n times derivative of X[1](t)"]);

I have a code like above. I run it. Then,

in the labels; it was written "n times derivative of X[1](t)"] why not "2 times derivative of X[1](t)"]) ? and why was not the subscript appeared ? I mean that I want to see X₁ instead of  X[1]?

Help me please.

Thank you.

I have a two graphics in two distinct Maple worksheets. How can I graph them on one graphic?

For example, 

 graphics of y=x^2 in one Maple worksheet named document 1, 

and graphics of y=x in an other Maple worksheet named document 2.

I want to graphics of them in document 1 by recalling the graphics of y=x in document 2.

Because, The codes that I will use in future are very long and complex, I need to write code like that. (if there is possibility) 

The writings in the variables palettes are overlapped. Is there any solution suggestion?