if f(x) = x, then a horizontal translation 7 units to the right is given by function g(x) = x - 7
You can visualize this by thinking about the location of the point (0, 0).
When x = 0, f(x) = 0
When x = 7, g(x) = 0
So x has to be 7 units more to get the same value for the function
For this example the answer is g(x) = (x + 2)^2 - 7