JEE Advanced 2025 Mathematics question

Let ℝ denote the set of all real numbers. Let f : ℝ → ℝ be a function such that f(x) > 0 for all x ∈ ℝ, and f(x + y) = f(x)f(y) for all x, y ∈ ℝ. Let the real numbers be in an arithmetic progression. If , and

= + 1),

then the value of

is .