Question

[Giang Lê]

tính nhanh

2155-(174+2155)+(-68+174)

2.\(\dfrac{3}{7}\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)

\(\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)\left(1-\dfrac{1}{4}\right)\left(1-\dfrac{1}{5}\right)\)

\(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right).\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)

chứng tỏ phân số sau tối giản vs mọi số tự nhiên n\(\dfrac{n+1}{2n+3}\)

Answer 1

[Kim So Huyn]

2155-(174+2155)+(-68+174)=2155-174-2155-68+174

= -68

( 1 - \(\dfrac{1}{2}\) ) ( 1- \(\dfrac{1}{3}\)) ( 1 - \(\dfrac{1}{4}\)) ( 1 - \(\dfrac{1}{5}\)) = \(\dfrac{1}{2}.\dfrac{1}{3}.\dfrac{1}{4}.\dfrac{1}{5}\)

= \(\dfrac{1}{120}\)

Mình ps có 2 câu à ^.^!

Answer 2

[Giang Lê]

cam on bn