By definition of the forward difference operator $\Delta f(x) = f(x + 1) - f(x)$ with differencing step $h = 1$:
$$\Delta\left(\frac{2^x}{x!}\right) = \frac{2^{x+1}}{(x + 1)!} - \frac{2^x}{x!}$$Express over a common denominator $(x + 1)! = (x + 1)x!$:
$$= \frac{2 \cdot 2^x}{(x + 1)!} - \frac{2^x(x + 1)}{(x + 1)!}$$ $$= \frac{2^x [2 - (x + 1)]}{(x + 1)!} = \frac{2^x(1 - x)}{(x + 1)!}$$अग्रगामी अंतर संकारक $\Delta f(x) = f(x + 1) - f(x)$ की परिभाषा से ($h = 1$ के लिए):
$$\Delta\left(\frac{2^x}{x!}\right) = \frac{2^{x+1}}{(x + 1)!} - \frac{2^x}{x!}$$समान हर $(x + 1)!$ लेने पर:
$$= \frac{2 \cdot 2^x - (x + 1)2^x}{(x + 1)!} = \frac{2^x [2 - x - 1]}{(x + 1)!} = \frac{2^x(1 - x)}{(x + 1)!}$$