Question

Bài 24

Answer 1

1/12+1/13+1/14+...+1/22+1/22+1/22+...+1/22=11/22=1/2

=>1/12+1/13+1/14+...+1/22<1/2 (ĐPCM)

Answer 2

Bài 23:

a) Ta có: \(\left(\dfrac{1}{4}+\dfrac{3}{4}+\dfrac{2}{8}\right)+\left(-\dfrac{5}{13}+\dfrac{-8}{13}\right)\)

\(=\left(1+\dfrac{1}{4}\right)+\left(\dfrac{-5-8}{13}\right)\)

\(=1+\dfrac{1}{4}-1\)

\(=\dfrac{1}{4}\)