If y is an image of x under the function f, we write it as?

x = f(y)

y = f(x)

x = f

y = x

The correct answer is: y = f(x)
This is the conventional notation used to represent the relationship between a function f, its input x, and its output y.
It reads "y is equal to f of x", or "y is the image of x under f".