Question

Chứng minh rằng:

\(\frac{3}{4!}+\frac{3}{5!}+\frac{3}{6!}+...+\frac{3}{100!}<\frac{1}{3!}\)

Answer 1

Đặt S bằng tổng dãy số trên.

=>S=3/4!+3/5!+.....+3/100!

=>S<3/4!+4/5!+.....+99/100!

=>S<1/3!-1/4!+1/4!-1/5!+.....+1/99!-1/100!

=>S<1/3!-1/100!

=>S<1/3!.Vậy S<1/3!
 

Answer 2

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