The range of function y = f (x) defined on R is [a, b], and the range of Zehnder function y = f (x-1) is [a, b]

The range of function y = f (x) defined on R is [a, b], and the range of Zehnder function y = f (x-1) is [a, b]

The range is [a, b]
From the image, the function y = f (x-1) is just the result of the translation of the function y = f (x) on the x-axis, because the domain of both is r, so the range will not change