Answer:
f(x)=2sqrt( x + 3)
Explanation:
We know it's a square root function because of the shape of the graph and it's moved to the left by 3 unit, so it has a d value of +3. We know it doesn't have a c value because it doesn't have a vertical translation as it's still at 0. For the a value, you can figure it out my substituting the graph points in and the values you know now then isolating and solving for the a value.