Update Math401_P1_3.md

content/Math401/Math401_P1_3.md

@@ -191,7 +191,7 @@ $$
 
 as $n\to \infty$.
 
-note that $\lim_{n\to \infty}{1-\frac{a}{n}}=e^{-a}$ for any $a>0$.
+note that $\lim_{n\to \infty}{(1-\frac{a}{n})^n}=e^{-a}$ for any $a>0$.
 
 $(n-\|x\|^2)^{\frac{n-k}{2}}=\left(n(1-\frac{\|x\|^2}{n})\right)^{\frac{n-k}{2}}\to n^{\frac{n-k}{2}}\exp(-\frac{\|x\|^2}{2})$