Showing that Fa ⊢ ∃x(x=a∧Fx)

Question

I'm trying to using natural deduction calculus to prove the above argument. The problem is I don't know what I should assume in order to obtain Fx, or x=a?

It's not apparent to me what I can assume that would follow with a valid discharge.

Answer 1

$\def\fitch#1#2{\begin{array}{|l}#1 \\ \hline #2\end{array}}$

$\fitch{1. \ Fa}{2. \ a=a \quad = \ Intro\\ 3. Fa \land a=a \quad \land \ Intro \ 1,2\\ 4. \exists x \ ( x = a \land Fx) \quad \exists \ Intro \ 3}$

Answer 2

After thinking about it a little it became clear - although only by chance.

My answer thus would be:

1. $Fa$ Ass(Premise)
2. $a=a$ =I
3. $a=a\land Fx$ $∧$I 1,2
4. $∃x(x=a\land Fx)$ $\exists$ I 3