# If $P_n$ denotes the product of binomial coeff. in the expansion of $(1+x)^n$, then $\large\frac{P_{n+1}}{P_n}$=?
$\begin{array}{1 1}=\large\frac{(n+1)^n}{n!} \\ =\large\frac{(n+1)^n}{(n+1)!} \\=\large\frac{(n+1)^{n+1}}{n!} \\ =\large\frac{n^n}{n!} \end{array}$