To shift a graph to the left, you must subtract a value from x.
g(x) = x^2 − 3
The entire graph is subtracted by 3, so the graph moves down.
g(x) = x^2 + 3
The entire graph is added by 3, so the graph moves up.
g(x) = (x + 3)^2
The x value is added by 3, so the graph moves to the right.
The answer is g(x) = (x + 3)^2, because the addition of 3 to the x value moves the graph to the left.