A).Bạn lấy 15 : 301 = 0,049

B).Bạn lấy 25 : 499 = 0,050

Vậy là \(\frac{15}{301}\) <  \(\frac{25}{499}\)

\(\frac{15}{301}< \frac{25}{499}\)( dựa vào tích chéo)

\(\Rightarrow A< B\)

Ta quy đồng tử số. Ta có tử số chung là 75:

\(\frac{15}{301}=\frac{15.5}{301.5}=\frac{75}{1505}\)

\\(\frac{25}{499}=\frac{25.3}{499.3}=\frac{75}{1497}\)

Do  \(\frac{75}{1505}< \frac{75}{1497}\)

\(\Rightarrow\frac{15}{301}< \frac{25}{499}\)

\(\Leftrightarrow A< B\)

TA CÓ:

15/301 < 15/300 = 1/20 = 25/500 < 25/499

VÌ: 15/301 < 1/20 < 25/499 NÊN 15/301 < 25/499

25/499 > 15/301

Ta quy đồng

\(\frac{15}{301}=\frac{15.499}{301.499}=\frac{7485}{150199}\)

\(\frac{25}{499}=\frac{25.301}{499.301}=\frac{7525}{150199}\)

So sánh:

\(\frac{7485}{150199}< \frac{7525}{150199}\)

\(=>\frac{15}{301}< \frac{25}{499}\)

Vậy \(\frac{15}{301}< \frac{25}{499}\)

a) Ta có:
\(\frac{15}{301}>\frac{15}{300}=\frac{1}{20}\)

\(\frac{25}{499}< \frac{25}{500}=\frac{1}{20}\)

Vì \(\frac{1}{20}=\frac{1}{20}\) nên \(\frac{15}{301}>\frac{1}{20}>\frac{25}{499}\) hay \(\frac{15}{301}=\frac{25}{499}\)

Vậy \(\frac{15}{301}>\frac{25}{499}\)

a)Ta có:\(\frac{15}{301}\)<\(\frac{15}{300}\)=\(\frac{1}{20}\)=\(\frac{25}{500}\)<\(\frac{25}{499}\)

Vì \(\frac{15}{301}\)<\(\frac{25}{500}\)<\(\frac{25}{499}\)

\(\Rightarrow\)\(\frac{15}{301}< \frac{25}{499}\)(đpcm)

Còn câu b  thì sao.

A =  15/301 <  B = 25/499

Ta co:

15/101>15/100 

25/499<25/100

Tu do,suy ra 15/100=75/500>25/100

giúp mik vs các bn 

Ta có \(\frac{15}{101}\)=\(\frac{75}{505}\), \(\frac{25}{499}\)=\(\frac{75}{1497}\)

Vì 505<1497

=>\(\frac{75}{505}\)>\(\frac{75}{1497}\)

=>\(\frac{15}{101}\)>\(\frac{25}{499}\)

\(a,A=\dfrac{1}{7.9}\) và \(B=\dfrac{1}{7}-\dfrac{1}{9}\)
\(\Leftrightarrow2A=\dfrac{2}{7.9}=\dfrac{1}{7}-\dfrac{1}{9}\)
Vì \(2A=B\left(=\dfrac{1}{7}-\dfrac{1}{9}\right)\)
\(\Leftrightarrow A< B\)
\(b,A=\dfrac{15}{301}\) và \(B=\dfrac{25}{499}\)
Ta thấy: \(\dfrac{15}{301}< \dfrac{15}{300}\) và \(\dfrac{25}{499}>\dfrac{25}{500}\)
\(\dfrac{15}{300}=\dfrac{1}{20}\) và \(\dfrac{25}{500}=\dfrac{1}{20}\)
Vì \(\dfrac{1}{20}=\dfrac{1}{20}\Leftrightarrow\dfrac{15}{300}=\dfrac{25}{500}\)
\(\Leftrightarrow\dfrac{15}{301}< \dfrac{1}{20}< \dfrac{25}{499}\)
\(\Leftrightarrow\dfrac{15}{301}< \dfrac{25}{499}\)
\(\Leftrightarrow A< B\)
\(c,A=\dfrac{5.6}{9.25}\) và \(B=\dfrac{18.4-18}{8.9+7.9}\)
\(A=\dfrac{5.6}{9.25}=\dfrac{1.2}{3.5}=\dfrac{2}{15}\)
\(B=\dfrac{18.4-18}{8.9+7.9}=\dfrac{18\left(4-1\right)}{9\left(8+7\right)}=\dfrac{18.3}{9.15}=\dfrac{2.1}{1.5}=\dfrac{2}{5}\)
Vì \(\dfrac{2}{15}< \dfrac{2}{5}\)
\(\Leftrightarrow A< B\)
Chúc bạn học tốt!