Question

s = cho 3/1x4 + 3/4x7+....+3/43x46 chứng tỏ s>1

Answer 1

\(S=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{43}-\frac{1}{46}\)

\(S=1-\frac{1}{46}<1\)

=>chứng minh bị sai hoặc đề sai

Answer 2

S=\(\frac{3}{1.4}+\frac{3}{4.7}+...........+\frac{3}{43.46}\)

=\(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...........+\frac{1}{43}-\frac{1}{46}\)

=\(1-\frac{1}{46}<1\)

\(\Rightarrow S<1\)

Answer 3

S = 3/1.4 + 3/4.7 + ... + 3/43.46

= 3 - 3/4 + 3/4 - 3/7 + ... + 3/43 - 3/46

= 135/46 > 1.

=> S > 1. 

=> Điều cần chứng minh.

Answer 4

s=3/1.4+3/4.7+...+3/43.46

=1/1-1/1+1/4-1/7+...+1/43-1/47

=1-1/47<1

Vậy s<1