What does "compute Aut(G)" mean?

[Hill]

Homework Statement

Let G = {a+b√5 : a,b ∈ Q} ⊂ R.
Prove that G+ = G is a subgroup of R under addition, and compute Aut(G+).

Relevant Equations

Aut(G+)

I know that Aut($G^+$) is the group of automorphisms on $G^+$. But what does it mean to "compute" it?

 

[Hill]

I think that it means

$Aut(G^+)=Q^* \times Q^*$

where

$Q^*=Q\setminus \{ 0 \}$.

Is it correct?

 

[sbrothy]

You wouldn't be from Arizona would you?

https://math.arizona.edu/~cais/594Page/soln/solnexam1.pdf

Nah, I'm on very thin ice here... Sorry.