Question

So Sánh

a)\(\dfrac{179}{197}\)và\(\dfrac{197}{917}\)

b)\(\dfrac{183}{184}\)và\(\dfrac{-184}{-183}\)

c)\(\dfrac{29}{40};\dfrac{28}{41};\dfrac{29}{41}\)

d) \(S=\dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{100}\)với \(\dfrac{1}{2}\)

Làm ngay nhé

Answer 1

d)

Ta có: \(\dfrac{1}{51}>\dfrac{1}{100}\)

\(\dfrac{1}{52}>\dfrac{1}{100}\)

...

\(\dfrac{1}{99}>\dfrac{1}{100}\)

\(\dfrac{1}{100}=\dfrac{1}{100}\)

\(\Rightarrow S=\dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{99}+\dfrac{1}{100}>\dfrac{1}{100}.50=\dfrac{1}{2}\)\(\Rightarrow S>\dfrac{1}{2}\)

Answer 2

câu b

có

\(\dfrac{183}{184}< 1\)

và

\(\dfrac{-184}{-183}=\dfrac{184}{183}>1\)

=> \(\dfrac{183}{184}< \dfrac{-184}{-183}\)

câu c

có

\(\dfrac{29}{40}>\dfrac{29}{41}\)

và

\(\dfrac{29}{41}>\dfrac{28}{41}\)

\(=>\dfrac{29}{40}>\dfrac{29}{41}>\dfrac{28}{41}\)

câu a vì dài quá nên mình lười