Question

So sánh các phân số sau

\(\dfrac{3}{7};\dfrac{31}{37};\dfrac{311}{711}\)

Answer 1

Ta có: \(\dfrac{3}{7}\)=\(\dfrac{6}{14}\)\(\le\)\(\dfrac{7}{14}=\dfrac{1}{2}\)

\(\dfrac{31}{37}>\dfrac{31}{62}=\dfrac{1}{2}\)

\(\dfrac{311}{711}< \dfrac{311}{622}=\dfrac{1}{2}\)

=>\(\dfrac{31}{37}>\dfrac{3}{7};\dfrac{31}{37}>\dfrac{311}{711}\)(1)

Lại có : \(1-\dfrac{3}{7}=\dfrac{4}{7}=\dfrac{400}{700}\)

\(1-\dfrac{311}{711}=\dfrac{400}{711}< \dfrac{400}{700}\)

=>\(\dfrac{311}{711}>\dfrac{3}{7}\) (2)

Từ (1) và (2) ==>\(\dfrac{31}{37}>\dfrac{311}{711}>\dfrac{3}{7}\)