Question

Rút gọn 2phân số rồi số sánh 

A 90/160 và 6/7

B 18/20 và 7/10

 

Answer 1

a)Ta có:
\(\dfrac{90}{160}=\dfrac{90:10}{160:10}=\dfrac{9}{16}=\dfrac{9\times7}{16\times7}=\dfrac{63}{112}\)
\(\dfrac{6}{7}=\dfrac{6\times16}{7\times16}=\dfrac{96}{112}\)
\(\Rightarrow\dfrac{90}{160}< \dfrac{6}{7}\)
b)Ta có:
\(\dfrac{18}{20}=\dfrac{18:2}{20:2}=\dfrac{9}{10}\)
\(\Rightarrow\dfrac{18}{20}>\dfrac{7}{10}\)

Answer 2

\(a,\dfrac{90}{160}=\dfrac{9}{16}\\ MSC:112\\ \dfrac{9}{16}=\dfrac{9.7}{16.7}=\dfrac{63}{112}\\ \dfrac{6}{7}=\dfrac{6.16}{7.16}=\dfrac{96}{112}\\ 63< 96\\ =>\dfrac{90}{160}< \dfrac{6}{7}\\ b,\dfrac{18}{20}=\dfrac{9}{10}\\ 9>7\\ =>\dfrac{18}{20}>\dfrac{7}{10}\)

Answer 3

\(\dfrac{90}{160}=\dfrac{9}{16}\)

\(\dfrac{6}{7}=\dfrac{6.16}{7.16}=\dfrac{96}{112}\); \(\dfrac{9}{16}=\dfrac{9.7}{16.7}=\dfrac{63}{112}\)

\(\Rightarrow\dfrac{6}{7}>\dfrac{9}{16}\)

B. \(\dfrac{18}{20}=\dfrac{9}{10}\)

\(\Rightarrow\dfrac{18}{20}>\dfrac{7}{10}\)