Double parentheses with three arguments, mathematica

Question

If I assign something like this to variable Res:

Res=Solve[6-5x+x^2==0];

What will do the following line?

Res[[1,1,2]] 

or

Res[[2,1,2]]

Answer 1

Let's examine the FullForm of Res to see what Res[[1,1,2]] means:

In[1]:= Res = Solve[6 - 5 x + x^2 == 0]
Out[1]= {{x -> 2}, {x -> 3}}

In[2]:= FullForm[Res]                                                                               
Out[2]= List[List[Rule[x, 2]], List[Rule[x, 3]]]

Hence:

Res[[1]]     = List[Rule[x,2]]
Res[[1,1]]   = Rule[x,2]
Res[[1,1,2]] = 2