Bài 8 :
Chứng minh rằng :
a) \(A\)= \(\frac{1}{2!}\)+ \(\frac{2}{3!}\)+ \(\frac{3}{4!}\)+ . . . + \(\frac{n-1}{n}\)\(< 1\)\((\)\(n\in N\) ; \(n\ge2\)\()\)
b) \(C\)= \(\frac{1}{2!}\)+ \(\frac{1}{3!}\)+ \(\frac{1}{4!}\)+ . . . + \(\frac{1}{2015!}\)\(< 1\)