If the image of power function y = f (x) passes through point (2,2), then f (9)=______ .

If the image of power function y = f (x) passes through point (2,2), then f (9)=______ .

Let y = f (x) = XA from the meaning of the question, because the image passes through the point (2, 2), we get 2 = 2A, a = 12, y = f (x) = X12, f (9) = 3