The graph of f(x) = x2 is shifted 3 units down to obtain the graph of g(x). Which of the following equations best describes g(x)?
g(x) = (x + 3)2
g(x) = x2 − 3
g(x) = x2 + 3
g(x) = (x − 3)2
g(x) = (x + 3)2
g(x) = x2 − 3
g(x) = x2 + 3
g(x) = (x − 3)2